I don't see how he's necessarily wrong. It's typical for -R to be more compatible with DVD and other media devices (such as the XBOX.) I use -Rs for that purpose, and I've never had one fail to run ... well, with the exception of a Sony DVD player that could read it fine but it just refused to play it (invalid region supposedly.)
I use +R for data, because -R is known to not last as long as +R ... whether or not that is true or just a myth is unbeknownst to me. I use both for media players and data as described above and I never have problems.