I still have a Corona (!) Jumbo in the garage, along with the ribber and colour changer for the Knitmaster 700. I thought I would work back up to using all of it. I decided I could knit pretty much anything I really wanted without the ribber for the time being, but might get the colour changer out at some point.
I would love to use the Jumbo - it's a lovely machine, but, short of using it on the dining table, I think I'd have to reposition the table I have the 700 on at right angles to the wall and put it on the other side, which wouldn't be too convenient.