LinuxCNC capabilities

I am an ex IT guy (degree in network security) turned custom knife maker and I recently bought a 1999 Mighty MV-40 bed mill with a broken Acromatic 2100 controller, rather than fix it (probably a corrupted file system or bios battery failure, wont know until the machine actually gets here) I am seriously considering just doing a retrofit with either Linuxcnc + mesa or mach 3 and kflop/kanalog in order to keep repair prices at a minimum down the road. (also, parting out the functioning parts of the current control will likely pay for the entire machine purchase price and then some)

I am leaning towards Linuxcnc at the moment but am wondering about capabilities. The machine specs state 400IPM cutting feeds, 600IPM rapids, .0004 accuracy and .0002 repeatability. I would like to maintain this if possible. Is LinuxCNC + mesa up to the task? I don't really care about the PC hardware cost, if I need to build a top of the line machine - so be it.

I will mostly be using small high feed mills at ~80-90 IPM for profiling stainless or 3/16ths flat end mills and HSM toolpaths. Secondarily I will be using it to machine micarta, g10 and carbon fiber at ~300 IPM.

Really liking the look of the application and the community here, surprised I didn't check it out sooner for my benchtop machine!

If you keep your current hardware then the machine specifications will be the same (only changing the controller).
If hardware will be different then you will have a better or worse machine.
The controller is only a small part on the machine. Servos, servo drives and the mechanics play a big role on the final quality of the machine.

Thanks for the clarification. I guess I was under the impression (probably from using Mach 3 without external motion control hardware) that machine performance could/would effect maximum pulse frequency/stability/jitter and overall accuracy at high speeds. Is this incorrect?