Hi, brujon!
An interesting idea you have there, which I have also already thought about a bit.
The answer, in theory (I have never tried this out so far?), is probably something like this:
With 10x wbl, non-casters get more powerful than casters, since the big shtick of casters (magic) diminishes in relative importance. However, this should be hardly noticeable, since such high wbl makes class abilities in general much less important when looking at a character's total power.
Meanwhile, a BBEG with 20x wbl is going to be quite nasty...easily multiplying in CR...
- Giacomo
PS @ JaronK: color spray forces wizard into melee range at low level = dead wizard.
Color spray is a big trap for a wizard player to choose. Way too risky.