I have 4 kinds of nipples that I have been testing. (Ok, no cracks about too much time on my hands or living in my moms basement) I found no nipples that fit CCI #10's well enough to guarantee reliable firing. They (the CCI's) were all too small. I fixed that by chucking a spare set of Treso's in my drill press and polished them down till they fit the CCI #10's.
I found that the Blomquist nipples were the best overall. They fit RWS's perfectly. They are also extremely hard. I accidentally tried to file it like I did the Treso's. No comparison The Blomqusists were much harder. I doubt that matters at all so take it for what you will. I think the Treso's are more than adequately hard.
Unmodified Treso's liked Remington #11's. Unfortunately, Remington #11's are tough to find.
Uncle Mikes liked #11's as well. CCI...not so good.
In fact, as far as fit goes, Remington #11's fit close enough for most all.
I used the following nipples.
1) Treso
2) Uncle Mikes stainless
3) Blomquist
4) Stock Ruger
As far as staying on after the hammer falls. The RWS's do seem to blow themselves apart and off more than the less powerful caps. However, it didn't seem to matter as far as causing jamming up the works. It seemed that when the RWS's went off and vanished. They were just gone. They really didn't seem to disintegrate and jam up the works.
The CCI's parts of the cap would tend to stay on the nipple more often than not but it was never the whole cap. Parts of them were always gone. I never found the full cap still on the nipple and many much of the time, they too vanished.