I've already basically done this and I sell it as a PDF on RPGNow.com.
{Begin Plug}
This is what
Character Customization does. The difference between it and other feature equivolency solutions is that it divvies up classes into chunks called tracks. A track is a 1-20 level progression with a few abilities attached to it. These tracks are balances with other tracks across all 20 levels. Thus instead of asking if Favored Enemy is equal to Raging. You ask, is Favored Enemy at 1st, 5th, 10th, 15th and 20th level equal to Rage 1/day at 1st, 2/day at 4th, etc, etc.
About the only real flaw with Character Customization (IMHO) is that I've been horribly delayed in releasing the 3.5 update for it. I plan to have it done by Summer. Really, I do. All the little things that changed in classes from 3.0 to 3.5 makes some of the tracks off-kilter.
{End Plug}