As far as DVD Video is concerned, Imgburn behaves different than other programs, say, Nero. There additional material is added at the end, while Imgburn puts them first. I experience no compatibility problems on my DVD players, but discs usually deterioate from the outer edge and then the video material deterioates first rather than the additional material, which is usually not as relevant. Thus it would be safer to put additional material at the end of the disc like most other burn programs.
I really like Imgburn a lot, but it's a pitty that alphabetical order is the only choice. Is it really difficult to burn the files that order, in which they were dragged into Imgburn? In that way one could arrange that more important files are better protected against disc deterioation.