Thanks for the responses everyone! I guess I'll just have to make one of the meets and discuss/drive with some of the locals. I think a tune is one of those things you just have to experience outside a discussion.
Yes, I'm a bit over the top as an mpg geek, but most of the really high mpg vehicles are decidedly not fun to drive. I bought the Focus because of reports that it was a good driving car, the significant aftermarket support and competent forums like FF. I think 40mpg is not out of the question. Even out of the D23.
The quest is on. Thanks guys!