I get wanting to have the newest of everything, but sometimes that's just not how it works best.
As a rodder, would you prefer a 69 Roadrunner have a vintage Hemi in it, or one of the newer variable displacement Hemis from the Charger? You'd want what was going to work best with your car.
Fact is, nobody with the know-how has completed the monumental task of making 4.2.1 work right with the Razr Maxx. There's still a few bugs in 4.1.1, and 4.0.4 yet. If you have the skills, have at it! I'd love to see it. I am entirely too uneducated to do it myself. I only know enough to root, sideload, and get myself in trouble.