I have the BabyLock Tiara, which is the same machine as the Sweet Sixteen and I love it.
One question with these mid arms is do you want the machine head oriented like a domestic or straight on like the Tiara/Sweet Sixteen is? I had no trouble getting used to the difference in orientation and find that it is easier with the open space to your right.
Rob and I both bought ours used and had really good luck, so that might be an option for you to look at as well once you decide what you're looking for. I got mine off of Craigslist with less than 500 000 stitches on it.
Watson
PS...once you get your midarm, have a look at Jamie Wallen's video's on tension and oiling. They are invaluable for getting started.