I know I am biased. I bought a gently used HQ 16 [not the sitdown model.] I added the ProStitcher when it first came out. I still love it!
HQ has excellent tech service via phone. I have even forwarded a text pictures to the tech with the results being great. A picture is really worth a 1000words.
Right now many quilters are trading up and there are some great deals on used HQ's.