It's an amazing machine! I have a longarm, so I got the 590, and LOVE the bells and whistles! I especially love the needle up "hover," for chain piecing. But love the option to have the foot stay down for long seams. I've learned that none of the 1/4" presser feet engage with the right feed dog. So to get the best 1/4" seam, I use my #34D presser foot and bump the needle position to the right 3 bumps. Then I feed the edge of the fabric just inside the feed dog hole. That way, both feed dogs are engaged with the fabric. I really struggle with free-motion and ruler work on my 590. I feel like the take-up lever isn't timed like my older Berninas, and I CANNOT FMQ without lots of snarls on the back. I do great with my 230, 930 and 830, but cannot get FMQ with my 590.
The 790 can do the extra wide decorative stitches, with the sideways feed. That's pretty amazing! It would be awesome for quilting borders.
I'll be doing some embroidery tomorrow! You have to tighten the bobbin case a LOT for embroidery. Or you can buy a separate bobbin case that's tighter for embroidery. I was a Bernina tech for 8 years, so I'm very comfortable with adjusting my bobbin case tension.
If you can get the 790, you won't regret it!