I don't think anyone actually has frame data and, judging from the fact that EX Iori, who isn't even released yet, has more pages in his thread than this guy, not very many people play him. So it's hard to get info that detailed unless we decided to go labbing (and I just might tomorrow).
I can say for certain that the D version is slower and can't be comboed into normally. I've only seen it comboed into when drive cancelled off a DP.
The whole "can't be punished by normals" thing seems kind of irrelevant since you can't combo into it and neither version, in my experience, is a good way to approach the opponent.
I have to admit that I haven't tried using the D version very much, but I'll have to do some experimenting with it. Are you sure that you can't combo into it off of like cl.C, f+A,A, or even just cl.C, f+A? I guess that doesn't really matter much, since that isn't a particularly good blockstring anyway, and that's what I was thinking about using it for. I haven't really noticed that qcb+B is unsafe on block, but then I haven't used it against anybody who might actually punish it anyway (since the AI is too dumb, and its pretty hard to punish stuff online).
One thing I'm almost sure of is that the two versions don't do different chip damage (since they do the same damage on hit), and I also think they do the same amount of guard meter when they're blocked. So unless qcb+D is somehow way safer on block, even if you can combo into it somehow, I don't really see the point in using one over the other.
Even if they are minus frames on hit (which I'm sure they are), it isn't very many, unlike dp+A/C up close.