I did the hybrid 'stat plus a grill block and it keeps the temps around 210F. I had the same problem with the factory 'stat ... couldn't keep it above 188F. Hard to say how much (or if) the new hybrid 'stat helped with FE since I changed several things at once. Overall the FE has improved since I put it in (FWIW).
Do you have any engine build details (pics, etc)? The text description is interesting but it'd be interesting to see the comparison of old vs new parts if it were available.
EDIT: Just noticed the link to your Flickr pics... that helps... a little
