To help decipher some of the information you might be seeking for your purchase, here is a brief desription.
Float 2 / This is a second generation air shock, that primarily addressed all of the issues that some of the above posts list. All of the internal parts were changed from previous Float designs.
These changes were promted from feedback from consumers directly to the engineers at Fox. This is basically an entry level type shock that is typically lighter weight then most coil overs, and still offers more adjustability then a standard shock.
Float R Evol / This shock also recieved all of the internal new parts that the Float 2 did, plus it added external rebound adjustment, as well as a secondary air chamber. This secondary air chamber helped create a more linear spring rate transition through the stroke of the shock shaft. Basically it allowed lower main chamber air pressures for better slow bump use, but still allowed it to ramp up the final spring rate in the last 1-2" of travel. Though from a technical point you can not use the rebound to assist or move the compression dampening, it nontheless has a small effect on compression dampening, and can definately be used for tuning purposes as long as you have a good understanding of its effects.
Also note; for all of the add on air chambers, there is no way to properly address a serious spike or ramp up between the main chamber and add on reservoir due to the size or oulet of where the schrader valve is located. It is like putting a 1/2" hose on a 1/4" oulet and expecting to see a large increase in volume. For the Evol chamber this port has been engineered to accept the larger flow capacity.
The Float X Evol / currently the best (though probably most misunderstood) shock on the market. Why? Because it a complex shock, and potentially more durable. For all of the posts that list its negative attributes, you may want to look at what has happened on the ATV market in regards to pro racing. All of the major winners are using this shock in a lot more rugged or demanding enviroment then snowmbiling. The combination of the adjustability (over 500 external adjustments used in combination with air pressure adjustmments), as well as the length of performance this shock delivers are part of the reason. (Did anyone look to see what was on the suspensions of the winners at the X games this year? Differnet brands, same shocks!
With the amount of adjustments this is where consumers can get turned around, and for lack of better understanding they either stop using them and or they sell them. With dual speed compresion dampening as well as rebound dampening, an individual can get lost trying to make the shocks perform the way you were expecting.
If you do not like to tinker with your suspension I would never consider purchasing a set of Float X Evols. You would be wasting your money. But....... if you do; then welcome to a whole new world of suspension tuning that really can externally cover almost every situation gravity can throw at your sled. Oh yeah, you may find your riding ability improving as well.
Hope this helps.
Tom
