IMO the issue of burned DVDs is a big mess, with landmines everywhere. The CD spec was very tight, and it's almost unheard of for a decent brand CD-R to fail to play back on anything. Not so with DVD-R. The spec seems to vary wildly, and incompatibility between burners, media & players is rampant.
At one time I hoped to use DVD-R to basically replace the CD-R. Sadly, in my estimation the reliablity simply isn't there.
BTW, by all account the Onkyo DV-SP1000 is a superb player. If you go that route I'll be anxious to hear how you like it.