The combro is excellent and does not suffer the same light issues as.a.lot.of pro chronos as it is breaking an infra red beam. These can be replaced. Robin Hewitt will also do a little insert that means you dont have to press reset each time. Handy.
Get the bore alignment tube .... safest way to use.
It isnt so keen on spring guns...but on PCPs its blindingly good.
You are confusing FPS with FPE. The gun should be set up to run at about 11.5 FPE but the true level is down to you. Bear in mind that the pellet weight and even things like head size CAN affect the power output between ultra lite and ultra heavy.
The Combro is good but its pretty much limited to pcp airguns imho. But it fits into a pocket and can be taken anywhere.
Thoroughly recommend Combro