Tested these at the weekend.
Dropping the pistons in I could use a lower LPR pressure, about 60psi rather than the 80ish. THe input pressure did go up a bit, but no more than 10-20psi and so I didn't notice it. Consistancy was possibly marginally better, but the paint was rather square so couldn't say for sure.
The bolt is great though, I was using some really old detents that were mashed to hell and they kept going with the detent grooves.
Only thing I suppose is I quite liked the way the stock bolt is cut to follow the outline of the top of the body, this bolt doesn't go back far enough to be seen.
Overall I'm keeping them all in and pleased with the £40 ish it cost in total