yes, high speed spindles, that is one key thing, I am and have been thinking about getting a 2hp router with a 30k spindle and modding my mill, there are a few problems, I would need to get some fast servos to keep up with the spindle, and I wouldnt be able to drill regular holes and do stuff like that because the minimum speed of them is like 6-8k
For 1mm end mills, 60k would be a little better
Jon