At my house I have the two routers listed below in my signature. The converted CMM router routes consistently faster do to its acceleration rate. It used to have some custom leadscrews at about a .25" pitch. I am in the process of replacing the leadscrews with ballscrews and a .3 something pitch (10mm). I'm also saving up for a motor, powersupply and controller replacement. All the details can be found in this thread:
Granite base CMM to Router Conversion
I can maintain just about the same acceleration with the same motors and can run the mill at higher speeds! I admit that my mill is under powered for 1/4"+ bits at medium to high speeds. The benefit is, I can carve 3d signs about twice as fast as my much larger Techno LC4896! The top speed might be lower on my CMM mill but due to the acceleration, it can finish 3d work much faster! With the new ballscrews, motors, and controller I think I can go much faster!