Wildman,
Caps do split, some more than others. Remingtons usually split at the crotch of the 4 petals. The big problem is not the splitting, but whether or not they fragment. The original design on the Colt's pattern pistols was to have the fired caps fall free of the cylinder as it is rotated. They won't drop free if they haven't swollen, burst open like a flower or expanded and split in some fashion.
The caps weren't "designed" to do this, that is just the nature of putting a thin walled copper cup with explosives in it over a hollow tube and then venting even more pressure back through that hole after the charge is ignited Colt just realized it was going to happen so he added a channel on the starboard side of the recoil shield and made the opening at the loading port generous enough that the caps had a good chance to fall free.
I haven't used thousands of RWS caps but I have noticed they do split when just snapping the oil out of the cylinders. Sometimes Remington caps do as well. I think the CCI caps do it the least when they are not on a charge, but they all open up on me when I use a charge on a .44 larger than 25 gr. This even happens with the Treso tubes. It isn't as severe and I find I get fewer fragmented caps which are the bane of the Colt's pattern shooter. If my caps open up like flower I rarely get a fragment and they usually drop off nicely and I have empty tubes when I hit the unloading table. I have more problems if they blow out a side and get wedged in between the tube, cylinder and sometimes the frame.
I find the Remington caps open up more predictably and tend to fall free, I actually have more problems with CCI and RWS caps. If I shot light target loads the CCI caps might be a good choice because they sometimes almost look unfired. They are loose on the tube and swollen a bit, but usually intact. The RWS caps in my experience fall in between the two, they split even if I use a light charge. They split but don't usually open up like a flower. The only RWS caps I really liked (actually needed) were the old 1055 caps which I needed for a '49 revolver I built from a kit over 35 years ago. The tubes were so small that #10s wouldn't stay on.
~Mako