If I were in your situation, I would look into a 26" tire. It would fit on your sportsman and most likely wouldn't rub, and you would also gain a bit of clearance out of it. Prices for 26" and 25" are normally real close, so it wouldn't be much of a cost issue.

 

Well since the factory 25" fronts tend to rub on someof the harder hits, I would not recoend 26" without ATLEAST a Progressive front suspension kit or High Lifter lift kit.

 

When I took my first ride on my Bi/Tri-Claws my machine darted all over the trail with every bump. It was so scary I couldn't even think about going over 30 mph. I found out that my worn steering stem bushings and tie rods had so much play that it allowed the big tires to bump-steer all over, something the stockers didn't do. I replaced the steering stem bushings and tie rod ends and tightened up any slop in the front end. I also did a little fine tuning on the toe-out. The result was well worth it. Although high speed handling is still not quite as accurate as with the stockers, I can still go plenty fast and regulary push it up to 50 mph on good roads. The last 3 days I've been going up to 45 mph on ski-doo rutted tracks across a frozen lake, or doing 30 mph on tight, winding ski-doo trails through the woods.
At very slow speeds (3-5 mph) in really rough terrain like rocks, stumps, etc, you do have to work a bit harder on steering. The difference isn't much though. In my mind the traction gains are well worth some trade-off, but it depends on what type of riding you do.
I know the 27"ers are a different tread and none of this may even apply there, but this is what I experienced for what it's worth.
Sorry to ramble on, but I hope it helps.