I just got the Janome 3160QDC and I love it. It's my class machine. It weighs only 12 lbs. but it is full size and has the needle up down and the cutter. The only thing I find lacking is the lighting, but I have a bendable bright light for that.
I do have a Jem 720, and while I do think it's cute and easy to tote around, I always felt like it was a bit too light - like I was going to knock it over. The 3160 also came with an extension table and a hard case.
Hope this helps!