There are improvements, definitely. It's just a matter of personal opinion if it's worth upgrading, because, c'mon, you say yourself that you and all your friends love it.
In contrast to the guru's opinion, and depending on just how much you use the PJ and how much $700 means to you, I think it's worth the upgrade.
HOWEVER, I truly doubt you can get that much for it.
I see two videogon ads, at around $1100, and I highly doubt they will be a "quick sale".
So, then, you have to ask yourself if $1,000 is worth it to you. Very likely even $1100 to get it, selling the 2000u for $900, but that's just speculation on my part.
If it was Space Cowboys, I bet it was an Art Feierman review.