i did a couple hour run through e-bay and CL checking out what's available. measured it out and found that i don't want to go beyond 13 inch. ey to eye. the spring rate doesn't worry me much for the reasons you mentioned. If i could find a pair of double adjustable Risse racing air/oil shocks like i have on my DH rig, i'd drop the dime on them in a heartbeat ...actually, it'd be a massive pile of dimes for those puppies. ... oooh ..that would be one of these, the other is on my bike.
http://risseracing.com/store/product...16924ab39429b3