Paul, I'd be more than happy to test whatever you come up with. I may end up with a Mongoose in the end, but at the moment the painfully slow nature of the ELM327 on the car side (and the way 'AT ST' works) has me clamoring for something/anything better.
Looks like we're neighbors, I'm not far from Ann Arbor.
I'm new to the forum, forgive my intrusion. Background... about 20 years writing software (these days on freenix and some tiny amounts of OS X... no Windows since 3.1... time flies!). My current projects are the usual in-car PC for infotainment/OBD/datalogging (MINI Cooper S, M roadster) and a more elaborate system for a FactoryFive (PC + Ethernut). In-car PC is currently FreeBSD on EPIA.