I've given the Grinding Gear and Death Frost Doom a first read-through, and they are pretty good, as I'd heard. There are some features that I'm not sure I'd use, and some mechanical choices I'd grump about, but I guess the only thing that I'd definitely, positively have to change is the d100 table in Death Frost Doom. I'd want something that fit entirely on one page and was easy to use quickly, like a dice map.
No danger of me springing either module on the local OD&D group in the near future, because I have no working printer or e-book or portable computer. Perhaps a blessing for the players!