When I went down the FAC route, in ~2002, I was struck by the increase in 'certainty' when shooting rabbits. 30ftlb does provide more certainty of a clean kill, than the 11+ftlb power level does. Prior to that it was imperative, if you wanted to reduce the chances of wounding - and who doesn't - you had to be, not just confident in your kit, but assured in your kit.

A 12ftlb rifle has a place in the shooter's armoury that is unmatched by any other. But there are times, and more times than we'd like, where a 30ftlb rifle is a better bet.