http://en.wikipedia.org/wiki/Optiarc = Sony + NEC
Wherever you read that, it's wrong information: DVD+R DL media booktyped to DVD-ROM is more compatible with DVD devices of all kinds.
This is so true, in fact, that most burners automatically booktype DVD+R DL media to DVD-ROM by themselves (it's set to do so in their firmware), which is probably why yours is being booktyped even though you disabled that option in ImgBurn's settings.