I'm afraid my archiving and testing are not very systematic. I don't usually go back and test my burnt DVDs, except when I need to get data off of them, which is not very often. But so far I haven't run in to issues, and have been pretty lucky with the DVDs I've used. I don't think I can recall a situation where dvdisaster actually had to recover from errors on any old DVD. Of course, it's a good idea to transfer valuable data from old DVDs to new ones every now and then, as they won't last forever.

I just tried a DVD from 2013 (Verbatim DVD-R, 16x, 4.7 GB) and it read fine, without any errors, and dvdisaster found that the checksums on it matched.

I usually try to use at least 20% redundancy, but will settle for less if the data's not very important. If the data's really important I'll max out the amount of redundancy (up to dvdisaster's limit, which I don't remember off-hand). Sometimes I'll even burn an extra DVD with the same data, both with dvdisaster error correction on them.

As for par3, I only heard about it for the first time today in this thread. So I have no opinions on it except to say that if it's an improvement over par2, I'm all for it. Backwards compatibility with par2 also would be nice.

Thanks for the info

Shame about the status of the dvdisaster project - as of 2015 the Mac OS X and Windows ports are discontinued.

That's just for the new versions. You should still be able to get the old versions and those should still work just fine.