Hmm... 4 wires, you won't be able to run this parallel bi-polar (faster but needing more current for torque) - I imagine it'll be little use in a CNC machine that you want to use like you half mean it. Half the holding torque of a motor you could buy on these shores for 30-odd quid...

Probably ok in a 3D printer - I'd avoid it in a router.

Yes, it's a way of saving on parts - but in reality you're talking about losing a handful of components which, arguably, allow you to build a more elegant machine. Despite this appearing to be a good idea, I imagine it would be quite cumbersome to build around...

Just my uninformed opinion!

Wal.