Catrin,

I'm going to also suggest you look closely at a FSR. Same age as you, and after riding both a 29er HT and the demo Trek FSR that it feels better on my body with the FSR. Esp over rocks, roots and the like that WI trails are covered with. And being sensitive to vibration/buzz, the full suspension pretty much removes.

I know they are a bit heavier - but in my case realize taking 30lbs off of me would more than solve that issue.

I'm fairly tall (5'8") but short reached, making me lean to WSD. The other issue is the WSD specific brake levers - smaller, easier to use. But who knows. One thing with MTB is not really gripping the bars, and feathering the brakes with a single finger (I keep thumb and trigger finger on the shifters, middle and ring on the brake lever). Could actually be easier for arthritic hands. Dunno.

In addition to their demo teams, I'm pretty sure both Trek and Specialized have demo/short term rent programs. Plus at least in these parts, several LBS offer weekend/day rentals. May give you a better feel for what you really want. I'm currently lusting after a Specialized Safire WSD....but the new Salsa full suspension 29er (Spearfish) has me interested. Won't be doing anything this year, but am pretty sure down the road there will be a FSR MTB in my stable.