You might miss the single step gearing of your 12-27 with 12/13/14/15 when riding with a group on the flats at 22-26mph. It is sometimes nice to pop up and then down a tooth for cadence adjustments at higher speeds. OTOH you will spend a lot more time on most of the centuries you tackle going up the hills at 7-12mph where that 27 and 32t are handy.
Have you considered doing the Cherohala century next weekend? I did it twice in the '99 and '00 editions and it is right up your alley, assuming motorcycles don't bother you.
Steve H.