The only problem I see with this is that some people (including myself) would rather have one system over another. I'd rather have just DT than a hybrid system, as having both makes me think the game would be even more unbalanced because of this.
As always (and I try to make this clear, but like you said, you weren't around for the old one)...
Everything is
optional 
And customizable. That means that I will offer a DT "fix" (adjusting DT values to fit other changes in XFO and better intrinsic balance to the DT system), a DR "fix" (eliminating DT in favor of DR), and a DT/DR hybrid system (utilizing both, where DR first adjusts damage proportionately, then DT subtracts from the remaining damage absolutely). For each of those three, there will be a "mild," "medium," and "hard" version, just like everything in XFO. So that's 9 options for the first alpha release. Judging by previous releases, there may be more like 15 or so options by beta.
Unfortunately, as The Castle pointed out, the GMSTs and NVSE options for DT and DR are sorely lacking -- one of the few areas where the engine and the esm actually devolved from FO3. The normal go-to is scripting, and I'll look into it (easy at least to change the armor on YOU, or even your TARGET, but not everyone everywhere, as armor doesn't spawn independently, but as part of a character). In the meantime, yes, I'll have to adjust individual armor values. Among other problems this presents, it *will* make it incompatible with armor add-ons like FOOK. FOOK, IIRC, uses an esm, though, so I can make a patch. It's just a TON of tedious number-crunching

I also hex edit (I don't use GECK except to compile scripts, which is mostly doable from TESsnip, too), which is nice for most things, but svcky for object editing.
Yes, it appears that DT will be the thorn in my side this time around. But last time, the thorn in my side was creating a hunger/thirst/sleep system and balancing everything about it appropriately, but it looks like they did the work for me this time (*yoink!*

).