As I said, little things. I use my trigger hand index finger to drop mags when Im in a hurry, and I found it a challenge to do repeatedly on the SICS. Mag latch is quite small and stiff. Im not a real fan of the pure vertica thumb position that youre forced to use if you go for a thumb over grip, and the hinge itself impedes the ideal thumbrest location. I also didnt really like how janky the LOP feels when adjusting it. It locks up great though. Bag rider is a tad strange looking too hah.
I do love the threaded mag latch pins, adjustable folder tension, machining quality, cheekpiece, and pretty much everything else about it.