I have had a Sweet 16 for a number of years. It is so old that they didn't have the stitch regulator available when I bought mine (I probably wouldn't have bought it anyway though; my Bernina stitch regulator for my 440 was gathering dust). I really love this machine. I can do traditional FMQ on it, and I am getting better and better at using rulers. I did find the sitdown rulers need some kind of gripper on the back. I used skateboard grip tape bought off Amazon. The manufacturers sell some too, but it is much more expensive. Hands-Quilter has videos about ruler work that are helpful. Don't get tied in to the videos that are specifically set up to advertise a specific brand of ruler; the bells and whistles aren't worth it (says the person who got stuck with a number of them!). I really like the look of ruler work.
I also recommend looking at Rhonda Bracey's blog (rhondabracey.com). She has well over 100 quilts posted that she has quilted on her Sweet 16.
Pam