Just realize that light weight machines will slide all over the table as you use them. An example is the 400 and 500 series Singers we have. They use a push button reverse and when you push the reverse you have to hold on to the machine at the same time or it will slide away from you as you push the button. Weight in machines is what makes them stay put as you are sewing with them.
Heavy machines are a pain to carry and move around, but when you set them up to sew they don't move around on you.
Also my biggest gripe about the modern machines (other than the plastic) is their lack of room under the arch. I like lots of room.
Other than that I have little experience with the newer machines and none at all with anything computerized.
Joe