The biggest attribute the AH Mossie would gain is speed. It would gain 5 to 15 mph depending on the altitude. At 15k, it would (should) break 383mph. I cant get AH's current Mossie to break 369mph in level flight at 15k regardless of weight (15k is its best alt for speed, 8500ft is 2nd best).
I've fired all the ammo, taken no ord, and burned the tanks to just a few gallons and 369mph is max. Did you know the AH Mossie will fly the same speed with or without the internal bay loaded w ord? Oh, and regardless if the ammo bins have been fired empty or not? I'll go dig up the differences in weight and post them... gimme a few. brb....
EDIT: A Mossie w 25% fuel, 2/500lb bombs in the bay, and full ammo weighs appx 18,913 lbs.
A Mossie w 25% fuel, no ord in the bays, and no ammo weighs appx 17,291lbs.
Both top out at 15k feet at 369mph.
That is over 1600lbs difference. I'm not an aeronautical engineer or physicist, but that makes a fella go "hmmmm".