The downside with Sherline is also it's upside. It's size makes it ridgid for small work, but then it's small. As for routers, you could buy a spindle and VFD, or get a SuperPID for your router. Also, with higher RPMs you could theoretically increase your feedrate, within the limits of your machine's ridgidity and spindle power. But they are two different beats, meant to do two different things. There is a 10K rpm spindle option for the sherline, and you could also retrofit a router attachment when you need more speed.