Omni + timing belt drive =?

[sphuss]

We're a fairly new team and after attending a quick-build, we've decided to swap the standard drive for a holonomic omni wheel drive. The easiest switch we can see is to use a belt drive system together with our 8" omni wheels. We have chosen to go with belts rather than implement a chain drive mainly for ease of switch and use. For you veteran teams, I have two questions:
1)Is the belt/omni wheel combination a reasonable idea?
2) Our wheel hubs don't seem to match nicely with the belt pulleys provided in the kit... is modifying the wheel hubs ever a no-no?

Thanks much for your help