Basically, I am trying to go a bit bigger than sligh, but I still want to be able to go under/around the slower midrange and control decks.

This fits more into the classical 20 lands, 20 creatures, 20 burn spells RDW shell. An aggressive curve with lots of burn and magma jet smooths out draws. Hordeling outburst makes rabblemaster bigger, is a big boost for foundry street denizen, triggers monastery swiftspear and often makes it possible to stoke the flames for no mana.

Mogis's warhound is an interesting card to me because bestow is really good against removal (especially 1 to 1 removal), it triggers prowess AND heroic, the +2/+2 can save goblin rabblemaster from being hit by crackling doom (or be bestowed on him to save him from bile blights, drown in sorrow and other 2/3 damage spells) and if I really need it, I can play it as a 2/2 for 2 onto an empty board or to trigger multiple foundry street denizens at once. He's kind of like a red griffin guide (minus the flying, unfortunately). In any case, it's very versatile.

The sideboard has scouring sands, eidolon and searing blood for other aggro matches, harness by force and revoker for midrange threats and planeswalkers and shatter to blow up whips, spears, halls of triumph, etc.