Well, hey there, Betty Jo! I made a point to see your mermaid on the second day I went to the Hampton show -- it's wonderful!
I have a pretty strong opinion on your question, I just hope I don't get strung up for it. If you're looking to quilt on a frame, definitely go for a mid-arm or long-arm. The 820 and 830 have no business being on a frame! They are highly computerized machines that do EVERYTHING. All you need on a frame is a good, solid straight stitch. And here's a very specific objection to using the 800-series on a frame -- visibility. The needle is tucked under the machine in comparison to it's flush-with-the-head orientation on a long-arm. This reason alone is enough to look beyond Bernina. Well, here's more... My mom has had the 820 for a year (bought it at the 2010 Hampton show) and she would heartily agree with the visibility issue. In order to see the needle well, she has to adjust her frame higher than is ideal/comfortable for using a quilting machine. And I'm sorry to say that her 820 has been in the shop more than it's been sewing properly at home -- you, guessed it, tension issues. Don't make light of these. It's heartbreaking to find that the project you just spent hours quilting has terrible loops and such -- and no amount of adjustments at home could make any difference. I've had an earful of her frustrations for a year! The latest -- her machine has been in the shop in Chicago since early/mid December! This year at the Hampton show mom was test-driving the long-arms. She's hoping Bernina will refund her money so she can put it toward an 18"-arm quilting machine and frame. I only hope Bernina will cooperate and make it easy for her.
I am a Bernina Virtuosa owner, and I love it! But from what I've seen of the 820, I don't think I could be tempted to buy one. I believe I see a long-arm in my future, and it will be the real thing. Bernina just tried to put too much into one machine on this one.
Good luck on your decision -- I'd love to know what you end up doing. I had a great time trying out the long-arms with mom last weekend, and will be researching them more through-out this year. So I'd love to hear what you find in your research and would be happy to share what I find in mine.
PS Okay -- I'm still getting the hang of this new (to me) message board. I accidentally saved this as a draft instead of posting it (again), and then realized there were two more pages of posts on the subject!
With that in mind, let me first say I agree with Keith and Eileen, and there was somebody else too, about the intimacy of sitting down to stitch. If you want to use the 820 or 830 sitting down, it might do very well. But consider whether you might want even more than 12" of space, in which case the George or the Sweet 16 would be great. If you already have a domestic machine that you really like and that does a lot (can't remember whether you already have embroidery), then adding a workhorse like one of those just for quilting would be all you need. The 830 might replace an older machine you don't love, though. But if you want to put it on a frame, I wouldn't recommend the 830.
Just my 2-cents...