JeanM

I like your setup very much. You're right. If you can give up a bit on the low end, you can indeed improve your efficiency significantly. OTOH, for other people the low end is where they need help, so they will need to keep the "dinner plates". BTW, if a 22 chainring works on an LHT frame you've helped the OP.

OP - Harris Cyclery offers a 13-30 "Century Special" that with a 22 tooth granny will give you a slightly lower low end than you have now and improve the mid range efficiency as described by JeanM.