Never rode the V-Strom but I have ridden the BMW. It's a nice ride. A twin would be smoother. I have owned a KLR600 and would get a KLR650 before the F650GS. Even more so when the 2008 KLR arrives later this year.
new bike - BMW R1150GS
old bikes - Ducati ST3 (RIP), BMW R1100R, R75 & R65, Suzuki Bandit 600, Guzzi V65SP, Kawi KLR600, etc.