First of all, KEEP the 910!!! Next, think about your budget and what you really want this machine to do now. While it's a good thought to choose a model to which embroidery can be added, that's a whole 'nuther (expensive and complex) pursuit. Many prefer separate machines anyway, in order to sew on one, while supervising the other embroider. If you don't yet do embroidery, make sure your choice meets your sewing and quilting needs first. Personally, I strongly prefer the 5.5mm stitch width machines for piecing and general sewing. I find it a challenge to make narrow hems and seams and do tiny, tight work, with the widely-spaced feed dogs of the 9mm machines. HOWEVER, only the 9mm machines have the auto thread cutter and of course the wider decorative stitches. If your 910 is in good health and you have the space, then you can always piece with it. The 820 and 830 are huge and heavy. You might need a new table or cabinet to handle the size and weight. They're also NOT portable. But, they have the 12" harps, built-in dual feed, larger bobbins, and the most advanced sewing and embroidery features Bernina has. The 820 (sewing only-can't add embroidery) isn't much more than than the 580, 6 series, or 730. I have the 820 and LOVE everything about it except the 9mm feed dogs, which I find challenging for piecing and narrow seams and hems. But the huge harp (you can even put it on a frame) and luxury sewing features are worth that one weakness. I use my 440 for precision piecing and tiny work (spaghetti straps, mini sock monkeys and all their outfits, narrow hems, etc). But I miss the auto cut, built-in dual feed, much larger bobbin, etc on the 440 sometimes. For me, multiple Berninas are the solution. The 6 series have a LOT to offer. I think the first decision is 5.5mm versus 9mm stitch width. Not everyone prefers the 5.5 as I do, so test drive both (and if course your final choices!) with your fabrics, threads, and sewing tasks, and go from there. If 9mm works well for you for your general sewing and piecing, that's great, because then you get the wider stitches and auto-cut. The 430, 440, 530, 550, 630/635 are 5.5mm machines. The 450, 580, 640, 730, 820, and 830 have 9mm stitch width. The 450 doesn't have auto cut, though. The 4 series need to be connected to a computer for embroidery. The 530, 550, and 820 can't embroider. I hope that helps. Take your time, test drive like crazy, but relax, because these are all superb machines. I have a 240, 440, 820, and (vintage mechanicals) 930 and 731. All excellent.