I have an HQ16, and I love it! Great machine. Haven't had any issues with it. I do mostly free motion on mine.

I got a Simply 16 with a 10' studio table and I love it. I didn't want to mess with the clamps and moving the quilt around. I did a test drive at my LQS. The owner of the shop and her husband came to set up and train. I upgraded from a Sweet 16 (which I'm looking to sell) and I am really glad I did.

HQ16 with stitch regulator
 

I have a Queen/King frame. I am not sure how to set the HQ16 on the frame to work with the Qbot. Any ideas?

I talked to HandiQuilter today because we have a customer who wants to convert her Sweet Sixteen to fit a Little Foot Frame. The Simply Sixteen is made specifically for the Little Foot frame. It doesn't have any back handle bars, and the screen and carriage are different. However, you can find lots of used HQ16 that can go on about any frame. It's kinda confusing because there are 3 different HandiQuilter "16" machines.

#1 is the original HQ16 (you can find lots of used ones, but I don't think they make them new any more).
#2 is the Sweet 16, which is a sit down machine -- no carriage or handle bars.
#3 is the Simply 16, which is specifically made for the Little Foot frame. It would take some adapting to make it fit on the other HQ frames, and I don't think they have kits to do that.

The Simply 16 machine will fit on the Little Foot frame and the 10foot or 12 foot studio frames. In fact, Handiquilter recommends the Studio frames to use with pantographs. (Although I think they will still work with the Little Foot. Just more fiddling to ensure each pass meets exactly when the quilt is moved.)