>> how powerful it would need to be to give me exceptional hold down.
Wow. That is a loaded statement. The phrase "exceptional hold down" can mean a lot of different things. I got away with a single phase rotary blower. Others need large 3 phase heavy duty machines that cost $5k.
This forum has literally hundreds of threads on the topic. I suggest spending some time researching your requirements and narrow your specs a bit more. There is no simple and easy answer to the problem you're trying to solve.
ShopBot Details:
2013 PRS 96x60x12 (Centroid upgrade)
4hp Spindle
12" indexer
Aspire
Rhino
Fusion 360
Ferrari 360
Prusa MK3S+
Prusa XL multi-tool