Just installed a Golden Tyre 90/100-21 front tire with a Nitro-Mousse insert. I am amazed at how stable my 07 KTM 450 exc is now! Just returned from my initial Borrego Springs testing and found that my front end has diminished deflection over rocks (by a lot), the bike tracks in deep sand at least 40-50% better than before, and is now much more stable at high speed. As a mater of fact, I backed down my steering stabilizer one number to loosen up my steering because I'm not used to being in control so much of the time! I'm basically relearning my bike. One other thing I noted, is that the rear wheel slides out on me "much less" then before since the front end tracks so well.
A couple of drawbacks about the Nitro-Mousse is that they are not recommended to be used for "long pavement runs" due to heat build-up. Also, they need to be re-lubed every 40-50 hours of ride time; but the offset for me is control! it's crazy good! If you can handle the drawbacks..then I recommend this setup! For me... it's much better control, and the peace of mind, of knowing that I won't be fixing a flat on the trail, in the desert, on a very warm day. I'll be installing a mousse in the rear when my Desert IT wears down a bit more. Just wanted to share my experience with you all.
Cheers! Mark