+R's seem to be much more reliable and problem-free in my personal experience and in the experience of half a dozen or so of my professional IT colleagues. Deep in the gory details (see Lkdog's links), the +R's have some technical superiority over the older and more "official" -R's. Most all units these days, both computer and consumer audio/video will read either equally well. I moved from -R's to +R's early on (2+ years ago), and my professional colleagues at work have done the same (both for data and video) - we've simply found them more reliable and trouble-free.
