I almost got my dad a set of the mudlites but after reading about the out-of-round and air leaking issues, I bought my dad a set of Bearclaws for his 97 Kingquad for Christmas. He thinks they're great. Here's some pics... they do have a flatter tread profile.

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I have 26" mudlites 12" and 10" back/front.

With the deep lugs it is amazing what my Vinson will go through. Even climbing large obstacles is easy....the big lugs pull you up and over. Incredible traction overall. These tires area HUGE improvement to stock.

I have 900 miles on mine and no problems whatsover .....no leakage or any of the above mentioned problems.

The 26" will give you more clearance and the bigger width a wider stance.

I think they did steal a bit of power, but the Vinson has gobs of power to spare.

For a Vinson I think the 26" 12 and 10 are a perfect combo. For an Eiger I dont know. the 25 xl might be the answer....or use low range.

As for the rounder profile giving a sportier ride I would have to agree, I replaced a smaller atv with flat profile tires and the ride was way different...harder to throw the bilw into corners and stuff like that

 

I have 26's on my eiger (2005) 9's on front 10's on back. Power loss on the 5 speeds is minor, tires handle very well in dirt roads and great in the mud, and snow.

 

vaderpitt, If you haven't already bought your tires I'd look into a set of interco swamplites. I just put a set on my 03 eiger manual and I'm very happy with them although I've only taken one 6 mile ride on them but it was through some gnarly ice and firm mud with a few steep but short hills thrown in. I bought the bigfoot kit with the interco condor-4 aluminum wheels for under 500 bucks mounting and shipping included! I think you'd also be happy with the other two choices you had in mind, lets face it the stockers are ok when they are new but as soon as they have noticeable wear on them almost any new tire would be better. Good luck!