Thanks Neale for the info, it's very helpful. Sam (CNC4XR7) on youtube is running the same models as I listed on his PM727M https://youtu.be/ZbIVjMqetR4
I have had a conversation with Jon Klipfel from Teknic regarding these models and I think they will be a good fit. Interestingly, Tormach are selling Clearpath motors in their 770M and 1100M servo upgrade kits, so another vote of confidence https://tormach.com/bundle-770m-servo-upgrade-kit.html