LSR GREG summed it up pretty good. All of the newer long-travel UTV's (Maverick, XP 900, Wildcat, Deere 850I, etc.) will share the pecking order of wheel travel constraints. 1st factor:
Tire dia. and bump travel. How close to the ground are you willing to let your car bump? Of all the UTV's I've seen, you will run out of ground clearance far before binding your cv joints. 2nd factor:
Droop. Again, most of the utes I've seen are limited by the excessive cv joint operating angles as the suspension droops. This is due to the mounting height of the front and rear diff's. They cannot be mounted below the frame line now, can they?
Shocks are not a factor that limits travel, due to the many options of extended and compressed length shocks available. Hell, I just finished building a Maverick that I used Foxs' 14" & 16" internal bypass truck shocks on the front and rear respectively. No silly liottle UTV shocks will keep a fabricator from achieving the desired wheel travel. I'm stroking the rear shocks at an ultra-low ratio of 1.3:1 for 19 1/4" of usable wheel travel, while the fronts are stroking at a respectable 1.5:1 ratio for just under 18" of usable wheel travel. Heres the 3rd and most important reliability factor when talking usable wheel travel:
cv joints working at compounded angles (i.e. extending the wheelbase w/out moving the differentials). The majority of the long travel kit manufacturers are guilty of this. I will give you a real-world example of this industry standard that is parking race cars alongside race courses around the world!
A stock Can-am Maverick has a claimed Horsepower rating of 101 H.P. On the dyno, bone stock, it will produce about 70 horsepower at the rear wheels due to work (horsepower) having to be transmitted through a compound angle. It is a fundamental certainty, and is easily calculated with basic trigenometry. The bad deal is that while Can-am pumps out more ponies at the flywheel/crank, it is at the same time introducing an un-acceptable radial load upon the cv's. The horsepower did not disappear into thin air, but rather was released by the way of excessive heat and shear loads as a result of the increased friction through the poor little cv joints. Here's your lesson:
I moved the rear housing back 8 1/2" on the Mav, while only moving the rear wheelbase back by 5", left the motor bone stock, and dyno'd it. I'm now getting 82 horsepower at the rear wheels! Most all of who seen our car race said it is being over-driven, and will not last. We'll see how it lasts at Vegas to Reno. I intentionally over-suspended, extended, widened and weighted it. It has an undesirable power to weight ratio of 20 lbs. per horsepower, but can reliably run into 2-3 foot deep whoops at 65 or 70 mph w/out upsetting the attitude or overworking the shocks. Weight bias is 46/54 front to rear respectively, so it flies straight and true. Enough boasting. The point here is that what travel you do get, you use well, and reliably. I properly measure wheel travel at the centerline of the tire, in a vertical path, and keep the wheel rate as low as possible by stroking as much of a long travel shock as I possibly can.
Beware of kits that extend the wheelbase and not the diff's, and say the longer axles make up for the increased wheel travels' demands on your cv joints.