I really like the GF geometry. My cake was way fun to ride but I had way to many bearing issues with it. I probably would be riding a hifi now if I did not get such a good deal on my titus. The hifi has a horst link so it is going to soak up the bumps and be a good climber. I also think all 3 models are well speced for their price bracket. My only problem with the hifi is its proprietary fork. Until (if) other manufacturers make a fork to that spec you are stuck with the manitou. My friend has a pro and he loves it.
I really like the trance also, I think last years model was better speced for the money but they are still a good value. The suspension is a rip off of the dw link, which some argue is the best suspension available. Everyone I ever talked to that had a trance had nothing but praise for them.
Don't have much to say about the stumpy and the rm as I have never ridden them. I borrowed a buddies blur lt for a quick spin once and it was a nice ride. Seemed to have great acceleration but I was also riding a tank that day
Of course YMMV and this is just my
Keep us posted on the test rides!