I have the hq16 stand up and my sister has the hq16 sit down with table. We have owned our machines for 10+ years. Never have had a problem with them. After this many years of owning our machines, we decided it may not be a bad idea to have them serviced. We both use our machines almost daily. We both needed new check springs, and Sis had to have a new belt. The only thing the service tech said was" the machines run like champs even though the grease was pretty dirty inside."
What I really like about the hq is support from hq. No matter how old your machine is, they will still stand behind their machines and give you free tech advice over the phone.
You should look on the hq website, you may find some really good deals on a used machine.
My complaint about the stand up model is I am too short the completely thread the machine from the front. My sis's complaint about the sit down model is not enough table top on each side of the needle.
Good luck!