I would like to get some inputs on a machine optimized for 3d wood carvings I am potentially planning to build.

Working dimensions would be 1500 x 1000 x 150 mm using rotating ball screw. Screw would be 1616 or 2020 for X and Y, and 1610 or even 1616 for Z to get faster Z traveling speeds. Rapids are not important that much. I would use mains powered Lichuan steppers.

It would use small diameter end mills, I was thinking about 40 000 rpm spindle with ISO20 er16 (1-10mm clamping range) or er11 tool holders (1-7mm) since I mostly use 6mm end mill for rough passes. 1.5-2.2 kW should be enough for these purposes.
something like this:

I would be doing really detailed carvings using 0.5mm, 0.75mm, 1mm diameter tapered ball nose end mills.

Because of small tooling, the gantry also could be lighter.

I would like to have ATC, but since these jobs usually take a long time, maybe it's a waste.

Do you have any suggestions on what could be optimized for faster carvings?
Thanks in advance.