Well I like the JD 6620s we have a whole bunch of the sidehill machines around me here. I think they are a fine machine for the money. A real big setup from a MF 550.
The IH would not be a bad machine but if I was going to get one I would go to the 1460 over the 1440. Plus you should be able to get into the 1660s for not much more money unless you are talking real cheap old machines.