there are a number of belt drive users here, ynneb for example. Axxus also built a machine with belt drive (see ynneb's gallery). Also look at Tim Koene's video of his commercial belt driven p&p machine.
Belts will be fast but for direct drive i think you will need big servos. (i am planning such a machine, 500W servos, 25mm HTD5M belt).
Rack and pinion is another alternative... i may go for this on the Z axis (200W servo).
Belt tension stresses the motor bearings..
Max. torque is limited on belt drives (depends on pinion size, belt tension, belt width, belt style,....) but should be good enough for a wood router.
No hands-on experience from me YET but maybe this helps you further anyway.