So Thursday I rented a Stumpjumper 29er. I absolutely loved it!!! I currently have a Gary Fisher Opie and I am looking to upgrade, so I rented this bike and rode out at Alafia this week. I want to rent a Gary Fisher HIFI 29er and give it a shot before I commit to buy...Right now I am definitely leaning towards the Stumpjumper though!!! Just wanted to share my experience.
It may have been said already, but the Rumblefish would be a more direct comparison to the Stumpjumper (Rumblefish has 120mm travel as opposed to the 100mm on the HiFi).
Try giving the local GF dealers a call. They may have one together that you can pedal around the parking lot. The G2 geometry is a love it or hate it deal. It took me a bit to get adjusted to my Paragon but ever since I dialed it in the bike has been an absolute blast.