fly pro vs fantom pro 29 sl

I would strongly suggest that you take a trip to Cycle Spectrum (there are several in Florida I believe) and test ride each model. (I would call first and make sure they have what you're looking for though). Or, for that matter, go to pretty much any bike shop and test ride a 29er and compare it to a 26. Some people love their 29ers, some prefer their 26" bikes more. It's really sort of personal preference.