(CNN) -- A powerful group of players known as the 'G-7' has sparked tumult amid accusations of a hostile takeover attempt.

This drama isn't being played out in a corporate boardroom but on the football field, as marching groups converge on Lucas Oil Stadium in Indianapolis, Indiana, for the Drum Corps International (DCI) World Finals on Saturday.

Fans fear this may be the last championship of its kind as the top seven groups -- who have dubbed themselves the 'G-7' -- threaten to break away and form their own touring circuit. On the line is the future of drum and bugle corps, a niche activity deeply influential in music education programs and related sales worldwide.

"They are the Formula One racing of the marching world," said Roger Eaton, director of marketing for the band and orchestral instruments division of Yamaha Corp., which has corporate sponsorship deals with many of the top corps.

Unlike high school and college marching bands, drum corps are independent non-profit groups composed of brass, percussion, and flag and rifle spinners. The 150-member groups rehearse and tour full-time from June to August and draw college-age members from around the United States and 15 countries in Europe, Asia and South America.

In the wake of the economic crisis, the G-7 want a new touring schedule in 2011 that will concentrate the top acts at shows in a bid to draw new fans and increase revenue for these corps. Opponents fear the move will further winnow support from smaller corps, and the activity will consolidate to only a few acts.

"As a guy who runs a small corps in the shadow of the big corps, you're worried about the fact that, 'oh my God, if they go away, then there's nothing left for us'," said Bob Jacobs, director of Jersey Surf.

When presented at a pre-season DCI board of directors meeting in May, the move was perceived as a power grab; members supporting the proposal were kicked off or tendered their resignation. The proposal was leaked to the drum corps fan site, Drum Corps Planet, where reaction has been largely hostile to the G-7 proposal.

One group director at the center of the controversy is George Hopkins, head of The Cadets of Allentown, Pennsylvania, whose push to introduce electronics and other changes to the activity have rattled purists. Over the years that has garnered Hopkins a raft of threatening letters and phone calls; his car was vandalized after a drum corps show, and one death threat was left in his mailbox.

"When I went to the police they asked, 'Do you know anyone who would do this?' I said: 'Thousands of people'," Hopkins said

Traditionalists fear Hopkins will pierce the last remaining veil that separates DCI's brass-based sound from their high school and college marching band brethren: Allowing clarinets, saxophones and other woodwind instruments onto the field.

"What people don't get about me is I love it the way it is, I really do," Hopkins said. "But it's not going to survive if we don't let other people in -- the next big wall is woodwind instruments."

From garages to the Lincoln Center

Marketed as "Marching Music's Major League," Drum Corps International is an offshoot of community bugle, drum and flag groups that sprung up across North America in the wake of World War I. But staid military drill has given way to fast-paced, whiplash moves and physical demands equivalent more to a college gymnastics team than a chamber music program.

"Drum corps used to be more of a neighborhood group rehearsing in garages ... now it's gotten so professional and just keeps escalating," said Jim Mason, artistic director of the Madison Scouts.

While distinct from marching bands, high school and college programs widely copy drum corps drill, music, uniforms and instruments.

"They are key influencers," said Eaton of Yamaha, which field-tests new equipment with drum corps. "We know if our products can run the test of time with what they're doing, they'll stand up to anything."

But as the expertise of drum corps rises, their numbers dwindle. When Drum Corps International was formed in 1972 as an umbrella organization for the activity, there were more than 350 competing corps in North America -- 38 years later, there are fewer than 50.

Skyrocketing costs and a mobile economy has eroded local support for these community-based groups, corps directors said. Costs to field a competitive 150-member drum corps, a traveling entourage of instructors and support staff now eclipse $1 million a year for top groups. Most participants are college-aged music education or performance majors who pay as much $3,000 in fees to train and perform with top groups.

The growth of year-round school programs presents new logistical problems in finding available facilities for corps to rehearse and sleep while on the road, said Dan Acheson, DCI executive director. And fluctuating fuel prices, as corps log 12,000 miles a summer, add to the worries.

"Transportation alone costs a corps about $180,000 a year," Acheson said.

The problems of drum corps "shows up as lack of finances, but it's actually about management ... the ability to comprehend and react to all the demands of running a $1 to $3 million non-profit organization," Hopkins said. "Most (corps directors) were teachers; there is no training ground for this, really.

"The whole evolution and transition from community service organizations to non-profit organizations has been difficult. I think that's the main reason why most drum corps have passed away, for lack of a better term."

Other financial models were tried before. Mason was the former director of the Star of Indiana, the first -- and as it turned out, only -- drum corps wholly bankrolled by a corporation, Cook Group Inc. The group was active in DCI from 1985 to 1993 before it morphed into the Tony-award winning act, Blast!, which brought drum corps-style performance to the Broadway stage.

"I made sure whether we were playing at the Lincoln Center to the Hollywood Bowl that people knew we came from Drum Corps International," said Mason, who returned to drum corps this year to help the Madison Scouts -- where he marched as a student in 1975 -- return to championship form.

"All I can say is I'm here for the youth -- I have a professional group. If you want to have a professional group, do it ... but leave this alone," Mason said about the G-7 proposal. "I am really strongly supporting DCI in this whole thing, and I'm really hoping the other groups decide to stay and do this with us."

Hopkins is optimistic a compromise can be reached to avoid a split with DCI.

"After the emotions die down and the season takes place, I'm sure we can structure something that will benefit all of Drum Corps International," he said.

"I'm still in tears today after talking to our kids last night about what they get from the activity, what they learn -- that can't be lost," Hopkins said Thursday. "We're just inside very threatening economic times and we have different ideas about how to address them."