I have built both the LR3(build thread) and the MP3DP V5(build thread)
The printer is harder.
ANY printer is harder.
The actual build is slightly harder because you have a little more involved wiring, you need to cut the aluminum plates, etc., etc.
However, tuning a printer to give you very good results, in my opinion, is significantly more difficult than getting the LowRider 3/4 cutting properly.