US 1: What a great topic !! I haven't made the exact same move as you, but have some insights for you.
I have a 35 lightning w/ 502 Magnum EFI's. I burn approximately 15 gals/hour at 4000 rpm and 60 mph spinning 23p Mirage Plus props through 1.36 ratio Bravos. I would expect that you would see similar fuel consumption with slightly better cruising speed with the 32.
As for selling your boat, I have had similar conversations with the dealer who sold me my boat. He has become a friend as well as a boat dealer. We ordered the boat with the 1.36 gears with the intention of adding superchargers. We also replaced the valve train with roller rockers and aftermarket exhaust - Stainless Marine. I have not yet made the supercharger upgrade.
All that said, his opinion is that I would have to restore the engines to stock before selling or trading-in.
Hope this helps. Best of luck to you.