Yep, the back tires have to turn 20% more than the fronts, before the electric hubs lock up on the polaris. And on both of them, its noticably harder to steer when the fronts are locked. You can lock the front when you want on the kodiak, you have control of which tires are engaged, and when. You dont want to engage the diff lock when you have good traction, and theres a rev limiter when in diff lock. The regular 4wd setting, works very well and steers easy. As long as the fronts have somewhat equal traction, itll be 4 wheel drive. If one tire is up, like going over a log, then the tire in the air will get the power, but if you need the one on the ground to pull, just pop it in to diff lock and the tire on the ground pulls. I havent needed to use diff lock much, the regular 4wd has gotten me though a lot of stuff just fine.
See if you can get some test drives on the two, and your wife too. I can see why people buy sportmans, the ride is very refined but I like having control over the 4x4 system, Id rather prevent wheel spin, than to react to it.. that and the way the belt drive goes slack, and the rear only engine brakeing, made me choose the Kodiak.