There isn't really much wrong with DE machines but IMHO it is easier having machines that are the same brand and vintage - parts can be swapped around if something fails to assist with troubleshooting as an example.

JP is a great machine.  Typical problems with JP is wear around the holes, side to side motor on the T-Rex.  Other board issues have already been mentioned.  There is also a common thought that the caps should be replaced as well due to corrosion underneath them which isn't seen until one fails and it is removed.