Cannondale Rush 5 or Specialized FSR XC Pro

The Hoff

Who thought it would be so difficult getting a full suspension bike. I want to move from a hardtail due to a bad back - riding mainly XC with a bit of rougher stuff here and there. I'm 5 foot 10 1/2 - I've looked at Trek Top Fuel - huge top tube on 19.5 inch which I'd need (63cm approx). On the opposite end of the scale the Stumpjumper FSR has such tiny cockpit - upright seat post making it very difficult to get right saddle setback. Without spending an arm and a leg I seem to be stuck between the Rush 5 and FSR XC pro - probably looking at medium in both. I don't want anything too heavy. I'm estimating these both come in around 29 lbs - manufacturers don't seem to like telling you the weights.

Any advice would be welcome.