Does anyone have any insight that might help me choose between these motors to drive my spindle? I am looking for a compact package (i.e. smallest weight or frame), but don't want to give up on speed or torque unnecessarily. It's a beefy moving gantry design and the motor is fairly far from the gantry, so weight comes at some penalty in terms of CoG and bearing loads.

The Brook Crompton goes to 90Hz which is nice, but the weight saving of the smaller TEC is significant (smaller frame). The larger TEC gives up some speed (5-70Hz), but has more power and torque at the same weight and frame of the Brook Crompton. The Universal motor might be the best compromise - similar to the smaller TEC but with higher power.

Brook Crompton 2.2kW
TEC 1.5kW
TEC 3kW
Universal 2.2kW

I'm likely to gear around 1:2-2.5, to get around max 10-12k rpm, looking at using a good range of cutter sizes (think anything that will go in ER32 collets, so 3-20mm, although it's tempting to also use shell mills and boring heads on the DIN 69871 spindle). Soft metals only. Tapping would be a bonus.

Ultimately this seems like a low risk decision as they're relatively cheap and all available in the same fitment, but I'm not a motor expert so interested to get a second opinion (and this less common way of powering a spindle is harder to read around). A servo would be nice, but I'm struggling to justify one. I'm likely to use a cheap VFD, 230V 3-phase (these notably seem a lot cheaper in 2.2kW than 3kW).

Side question, how far above the manufacturers' top rated speed is typically reasonable?