Hey Dan,
I am still experimenting as well. With a heavily loaded rig, ie. packed roof rack, all seats filled with passengers, gear, fridge full of beer, etc... you may need to step up to 864's (ask Amando-he just did this

.
My opinion on the 863 is that they are firm but not harsh. I prefer the ride, but want the LEAST lift required to run 315 tires. I cannot comment on the 866 springs you are currently running.
Regarding the front end, I think the pic may exaggerate the difference - or i need to crank up the T-Bars

.
People that ride in the truck comment that the ride is nice - something they probably didnt expect from the lift and tires. I think this speaks highly to how well built and solid these machines really are. The OME springs only enhance this feeling.
Good luck with the "spring dilemma"
-Mike