If you're asking about NSK micromotors, I've used the same Electer model for 20 years, and it has been fantastic - smooth, vibration free, fast, with plenty of torque. I've sent it back twice for new bearings, but at least one of those was definitely my fault (grinding abrasive material).
I don't see any advantage in engraving for the 45 degree head other than to create additional heat with the transmission gearing and maybe adding a little awkwardness. Maybe if you plan on using it down in deep holes?
So, two thumbs up on NSK micromotors, thumbs down on the 45 degree. Hope this helps?
i've used a 90 degree head with speed reducer to add torque when running a one inch diameter sanding disk. works well and fits into small places. like having a mini side head grinder.
NSK is high quality equipment.
craig