Choosing new drives and motors,

I want better acceleration and more speed.

i have nema 23 381oz kelling steppers motors with g540 drive and 48volt power supply.
ball screws are 1605

my machine can just handel 5000m/min in two axis. its a moving table 500x600mm work area setup to to cut 7075 all day long.

i think i want servos and new drives and dont mind spending $300-$600 per axis what the options?

Also Vector drives?
i got the hitachi inverter for my 2.2kw spindle but i didnt get the vector drive... version sj200 or something?
What difference will the vector drive have on the 2.2kw Chinese spindle with bigger tools at lower rpms?

thnaks charlie