[techhelpbb]

Cheap CNC milling/engraving machines tend towards open loop steppers.
Steppers deliver maximum torque near the lowest RPM.
If you go too fast you miss a step and then your computer can not see that and everything gets offset till you ruin the work.
Mind you 3D printers and plasma tables use these same motors but the forces acting against movement are magnitudes less.

MaxNC put encoders on their closed loop axis steppers.
If they miss a step they try 8 times then give up and stop.

Servos with DC brush motors are available but add to the machine cost quickly.
IMSRV makes a Globe motor reduction to bolt on in place of a NEMA23 stepper.
At the cost of a new control and a few hundred an axis.
Really good machines use brushless AC motors for the servos.

Rigidity comes into play. As you push tools into the aluminum it 'pushes back'. A frame rigid enough for wood or plastic may not be rigid enough to push into aluminum without deflecting making the cuts worse or breaking tools.

Even my MaxNC uses a Taig spindle. That spindle is turned by a Baldor Universal AC/DC motor and maxes out at 3,000RPM. There is a single stage reduction. I could go faster but my steppers can not provide the force to move to match the spindle speed.

If you must run a high speed palm router for wood you can get a SuperPID that will slow it down so you do not rub the cutter. However you give up some HP in the trade. Good spindles are closed loop and will hold RPM even under cutting load.

By the time you optimize that X-Carve you are over $2,000.
Someday I want to take FRC parts and make a router suitable to build FRC robots.
Probably have to float a battery to handle the low voltage CIMs but it could be done.