I think the most efficient changing of gears is whatever works for you. I typically stay in the big ring on my road rides, but the guy I normally rides with stays in his smaller, yet we run the same speed. On my commute I am running a single chainring, and so far really like only shifting the rear. I don't have the top end speed, tops out around 24mph, but for my commute it is more than enough. I don't think I would mess with changing your inner chainring, it won't make that big of a difference.