I tried with TDK DVD+R, LG DVD-R and MAXELL DVD-R. In all of them I got an error message,
As it's 2.4 kernel and it logs timeout and resets the bus, there is a *possibility* for following scenario. As mentioned long time ago 2.4 kernel does not respect command timeout values passed along with ioctls deployed by growisofs. Instead, kernel sticks to hard-coded value of 30 seconds. Which is more than enough for vast majority of units, but if OPC or whatever takes longer, then you'll observe timeout and bus reset *despite* the fact that growisofs instructs the kernel to allow the command to execute for up to 2 minutes. *If* this turns to be the case, then DVD+RW kernel patch should make it work and so does 2.6 kernel. I'd recommed latter, as patch was not revised for long time...
If I use the same, not another one, but the same midia at SONY DRU 710, it records all data. I mean SONY DRU 800 didn't burn anything at the disc. I could burn a MAXELL DVD-RW and PHILIPS DVD+RW with SONY DRU 800. That means it burns only rewriteble midia, I think.
All this does not exclude yet another possibility, besides poor media support and kernel deficiency that is. Your 800 unit might be simply defective. A.