I really like my KM3 M/T's so far.The ride is pretty much stock like. After all, it is virtually the same suspension (coils, shocks, arms). The drop brackets helped keep the caster so it rides well. The 3.5" backspacing is definitely a must if you are going to run 39s with this small of a lift. Even now, I rub the fenders. I'll be separating the fenders soon enough to help with this. Also, I love the KMC beadlocks as I've had success with them on other rigs. The holes in the ring allow water to escape, I've never once sheered a ring bolt, and you can get to the backside of a bolt if one was to sheer off.
The 39's are about 37 1/2" now after 5,000 miles and 30 PSI. I like the 39s because they are bigger than a 37 and weigh less in some cases...also I am just a BFG fanboy.