I have an HQ16 on a frame. No doubt I tortured it in the beginning; it's a very hardy machine! I bought it 2nd hand in 2010 and have never looked back. My DH cleans it or me annually, other than that I have not had any maintenance done on it. one of these days it will need maintenance, but until then, I'm happy.
The only thing I would change about it is the throat size...in my dreams!