Have you considered the Duet WiFi or Duet Ethernet? They are not cheap, but they come with a lot of features including five TMC2660 drivers on board supporting up to 256x microstepping and controlled by SPI. Up to 2.0A current per motor they don't even need a cooling fan. RepRepFirmware currently limits them to 2.4A current in firmware, but we hope to increase this to 2.8A in time..
If you think that support for the Duets might not be as good as you get for RAMPS, ask at [
www.duet3d.com] for user experiences of support.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
