I have the AA s400. Epic rifle, not too heavy but not too light either, very well balanced. Imo.
I use the pump(fx three stage pump) does the job nicely, you don't need to be super fit to use it either.
I have the magazine conversion on it where you index the next pellet with your thumb so it good for in the field or remove it for single shot at the range or hft.
Never shot the multi shot but own an bsa r10, so can't comment on the multi shot. But if it's anything like the r10 you won't go wrong.
ATB.