Just finished building F-91 last week. It is indeed impressive for Bandai to come out with this kit that it doesn't require any polycap for the joint. However, because I too used to the polycap, I have to be extra careful with this kit, 'coz spraying at the joint means trouble. Because it is completely polycap-less, therefore the joints are made tighter than the usual polycap joint. Thus, because of this, I broke the right hand's joint, making it a handicapped F-91. So I have no choice but to modify the joint a bit in order to stick the hand back.
Even thought so, I still have another F-91 kit awaiting me - F-91 custom colouring from Crossbone Gundam series. I left with the outer layer of which I still hasn't started yet.