I'm surprised that it took so long for the sub vs. dub argument to come up in this topic. Over at GameFAQs, the first several posts were people raging at the fact that Gintama would very likely not have a dub, and then people were saying that the release was better off by not having a dub, and it went on from there.
Either way, ignoring the fact that I've been strongly anticipating a dub by FUNi or any other company that could manage a Shin-chan/Sgt. Frog style dub, there's not just the fact that there are already legal subs on Crunchyroll, but said subs will will, at any given point, be far ahead of any reasonable DVD release schedule, and all except the newest episode will be free. Plus, it's not hard to imagine that the DVRAB would just copy the Crunchyroll subs anyway. It just doesn't seem reasonable to buy, or even rent, the sub-only DVRAB.