[RJ]

Hmm. Well, since I haven't done anything with DVD audio I can only speak for data DVD and video DVD.

For Data DVD the DVD+RW's advantage is the background formatting (used for packet writing), and also Mt. Rainier support. Although only a few DVD burners so far support Mt. Rainier, it can be expected that newer DVD burners support it (like CD burners. Now every CD burner is Mt. Rainier equipped). For DVD- there is no plan yet to support Mt. Rainier.
Other than that, there is no advantage of DVD+ over DVD- for data.

Now for the DVD Video, I don't only think about the computer's drive, but also standalone recorders. VHS's quality isn't good enough and S-VHS is too expensive (okay, dvd recorders are very expensive, too, but comparing to S-VHS they are very new and the price comes down to an affordable level). DVD should be the successor of VHS, and a standalone DVD recorder should work as simple as a VHS recorder does, just with DVDs, so you can record original TV quality to DVD. That is the task that DVD-R/-RW just can't do in a comfortable way. Only DVD+R/+RW, due to its extra signal on the disc, that belongs to the lossless linking technology, you can always add another clip while maintaining DVD video compatibility. I mean, you just insert the disc, record on it, eject it and you can play it back on every DVD player that is capable of reading the DVD+RW (and very much players do).
With DVD-RW it's not possible. You can record in "compatible mode" only once. So you insert the DVD-RW and record. And when you stop recording you can't record more on the disc, you rather need to erase the disc in order to record on it again. But it's DVD video compatible, you can watch the DVD-RW in every DVD player that is capable of reading the DVD-RW.
When you choose the other mode, video mode or how it's called, you can record, stop, record again, but then it's not a video DVD anymore, and no dvd player will play it back. Well, that's not the type of recorder I want.
So that is the advantage that DVD+R/+RW offers for standalone recorders. This is called DVD+VR. With the appropriate software you can also use DVD+VR on the PC.
If you don't have or want a DVD recorder in the future you might not care about that, but personally I don't like the idea of having two different formats for standalone recording (which should replace VHS) and PC recording, as normal data burning as you're used to with CDs is also possible with DVD+R and DVD+RW, so you have no disadvantage by using them, so I see no need for the minus format.
I own the HP dvd200i, a DVD+R/+RW burner for almost a year now, and the DVD+R discs work in all DVD players and DVD-ROM drives of my friends and relatives. The DVD+RW discs work in nearly all. One DVD player and one laptop DVD-ROM didn't read them, but all the other player played it back without a hitch. That's what I can tell about my personal experience with the compatibility.
The speed of DVD+R and DVD-R is currently at 4x, DVD-RW is at 2x and DVD+RW is at 2.4x and in some regions of earth there are even 4x DVD+RW available.
You're right, I can't 100% say which format will win, as I'm no wizard. It's just that DVD+R/+RW has the most advantages for data and video, the media is quite cheap (minus media of the same speed class is not cheaper, sometimes even more expensive) and very compatible. Most manufacturers decided for plus and therefore I also see this "Real DVD" campaign in the US as a sign of the few DVD- supporters getting nervous and still trying to push DVD- to the standard, whereas plus has the growing support behind it. Since DVD burners are now quite cheap (they are now the same price I paid for my Plextor CD burner in december of 2000) at least here in Germany we expect the disounters to sell cheap PCs with DVD burners, and they will likely be plus.
But what I also doubt is that by next year a blue laser technology will replace the current DVD. That is something that will take quite a few years, as no DVD player is capable of playing them back, and at least here in Germany there is no HDTV, so no real necessity for blue laser, and there are already three different formats out there. If even DVD- vs DVD+ isn't finished yet, I can't imagine that the battle of the three blueray technologies will decide soon.

RJ