The MFR - once fettled by Ben Taylor - is purported to shoot 45-50 shots at 25ftlbs.

That is a LOT of bunnies from one cylinder.

A Daystate MK3 will do a similar number at the same energy but has the advantage that you can adjust the power level up and down.

i.e. MAybe get 100 shots at 18ftlbs for some work or 50-60 at 25 for longer range stuff.

Just a thought.