"With SPRiT 68g SLOW you crash into the bottom, the force curve is literally flat. No spring I tried is that flat.

MP68g on the other end is progressive, it's easy but consistent to press and gets a bit round (bit stiffer) towards the end. Gateron yellow is a bit like that, but 68g MP is a bit more progressive and a bit less heavy (Gateron Yellow was a bit heavy for my taste)

It ain't cheap but I personally really like its force curve

Probably my end game linear spring"