I also have a sitdown (due to medical conditions) Sweet Sixteen and love it!! While I haven't used it enough, it is very simple to use and just awesome! I didn't want the stitch regulator, but it may work differently on the Simply Sixteen. Definately take a look. They always say to buy the very best you can afford. Check out how you load the quilt etc. Good luck- Mine is 1 year old today...the dealer drove it up to my house!!
Oh, there is also a Sixteen club (blog) you can join...