On most systems no. That doesnt mean you can't build such a system though. As pointed out if you are building a stepper based system the need to close the loop isnt that great.
Not really. There are whole ranges of servos solutions out there that would never be useful on a router. Finding suitable servos for a router sized machine isnt that difficult. The problem for most of us is the cost.
While I agree, I think true servo drives on a smallish type router would quickly move into the overkill range.
Closed loop steppers are a new beast on the market. At least they are new to me. Honestly i dont see the point as these days you can buy servo drives that take step and direction control effectively emulating stepper behavior.Thats why I was exploring closed loop steppers.
In any event id like to back up a bit here, there is a lot more to precision and repeatability than the electroniics. Once a stepper or servo achieves an angular position it is up to the mechanical system to repeat and give you the precision you want.
I spent years working on lathes machining optical parts and have to say it can be extremely challenging to achieve high precision results. You can have the finest encoders and servos that exist but you are still limited by what is happening in the mechanical world. Now that is an extreme world motion control wise compared to a router but the point here is that you need a good mechanical design to achive high precision and repeatability. The controls are part of the solution.