Hey,
I'm all for supporting the programmers who have designed P2P shareware, but upgrading to Limewire Pro has been a major disappointment: downloads aren't any faster, and may in fact be slower (don't ask me how; I'm confussed about it myself). I've been all day attempting to download several files of interest and have not been able to download one!
If you don't mind paying for (non existent) membership service, then upgrading is a very fine thing to do. But, personally, I don't think the programmers who designed the software really designed it to provide anything extra to members who upgrade to the Pro service. So in my opinion, I don't think upgrading to Pro is justifiable: there is nothing to upgrade to! The programmers forgot to go to work the days they were writing the upgrade software and there is nothing of it to be found: they don't deserve your support: the upgrade sucks!
IMO.