While i do not have the smart parts apex set-up i do have the Empire Super Freak Barrel Kit for my Axe. I prefer to play speedball, hyperball and airball so naturally i do not get use of it there. But when i play woodsball i will use it about 1/2 the time. Also when i played in the clowns vs zombies game at PB Explosion i had it on the whole day. So as far as it just staying in the gearbag (or in my case, cardboard box full of gear) i would say no it does not.
As far as the paint, the most brittle paint i have used it on is GI 3 star and had no problem with it. I have had a couple breaks and as far as cleaning, i took the apex off and used my swab on both the apex and back, then counted my next 5-10 shots as "clean-out" shots.
Hope this helps