If this is of any help, I’ve had a Factor RC for a few months now (since March), fitted with low-profile rings and a Burris Veracity scope.
Since my main use for this pcp is chipmunk extermination, fpe isn’t a major consideration. In the few months I’ve used this rifle, I’ve put about 1600 pellets through it, and I’ve observed the following:
1) very reliable- it has not presented any functional/operational issues
2) accurate- with regulated pressure, many rounds of hole-in-hole groups are common- slight deviations of poi due to temperature (fully floating barrel)
3) this pcp rifle is heavy- definitely not for freehand shooters, I use it mostly on a tripod- carrying it would be cumbersome.
I actually dialed it down a bit from factory regulator settings of 140 bar, to around 840-850 FPS, with 18.21 gr (H&N Crow Magnum) pellets. Better near-range accuracy and shot count per fill- the lower velocity also lends to to better energy transfer- it literally launches chipmunks.
In summary- I guess lots of PCPs would be pretty effective in shooting chipmunks- but this PCP does it’s job very well.