I have the HQ16 with stitch regulator. That is the only difference between the sweet 16 and hq16. I absolutely love my hq. I have the HQ16 with the 10ft QuilTable. FAN-TAB-U-LOUS.
The hq is a very LOW MAINTENANCE machine. Just keep the bobbin area clean, 1 or 2 drops of oil every 8 hours or so and voila you are done with maintenance. I've had my machine for over 3 years. I've finished AT LEAST 100 quilts on it and have not taken back to the tech for service. I MIGHT, not too sure yet, but MIGHT take it to be serviced sometime this year.
The machine runs fairly quiet. I have very little vibration or machine bounce. Whenever I do get that I just have my husband re-level my table. Poof, no more shakey.
Look on the handi quilter home page in the forums and you can find some really good deals on machines because of the release on the Avante and Fusion. Also, I think there is one on mqresource for sale at a good price.
You might contact a few HQ dealers also. They may have some for trade ins. Good thing is, even if you buy one used, HQ will still help you if you have any problems. They are absolutely FANTASTIC folks. They are a company that believes in standing behind their product!