Cube Stereo 2011 Shock options

Well after a full service it appears that my Fox RP23 BV rear shock needs a serious service as the propedal function has absolutely no effect, even after a full seal service from me and even an air tune...after looking at likely costs it seems a cheaper option to look to replace with new! Can anyone suggest a good replacement? the shock cant be much bigger than the RP23 BV unit due to it's location between the seat stay and the rear wheel! Current shock is an XV2 air can, with Medium settings. I'm 17st so needs to cope with that as well....any suggestions please?