I haven't encountered other happy customers of it, but for a bolt-on closed loop upgrade I'd recommend MKS SERVO42 series. It's a hobbyist type product that com

I haven't encountered other happy customers of it, but for a bolt-on closed loop upgrade I'd recommend MKS SERVO42 series. It's a hobbyist type product that comes from AliExpress no enclosures or safety protections, and slots right into RAMPS driver ports. It just needs an initial calibration, no software changes needed at the host side.