Watson ... I think Rob has given you a good rundown.
I totally forget what the upgrades added on, but I know when I saw the 2nd listing, there were some features that definitely I thought were better than the original (that I have). Likewise, the 3rd. Of course, all in perspective, based on $$ ... and whether you are looking at used or new.
Don't hesitate to call Handiquilter and ask them all you questions! When I was shopping, I found that a lot of the dealers really did not have the answers (aka did not know their product!), so I called through to HQ, explained my situation and they were wonderful, with all the time in the day for me.
RRyder ... some people still don't seem to like the idea of spray basting, you and me not being in that crowd!
However, I can see it would be an asset if that were the case. Though, there may be times that one might want to machine baste .... not really sure right now when, other than to eliminate pins. But that'd be double work, first pinning and then basting. I guess the upside is, that you could baste the heck out of it, and if it got bunched you could remove and start again.