Toad,
I would say yes although not a great result.
Yes you do gain about 300FPM from the loss of 1,000lbs in the F4U which BTW equates almost exactly to 1/2 fuel 1/2 ammo. However the climb time for the F4U-1D in AH is already a bit slow to 20,000FT by about 30 seconds. It may not seem like much but the loss is really above 10K I would say so it is in a short climb span and the thing barely climb anyway so it looks even worse.
So in short it does realize the gain but in the end the times don't quite match the charts although it is very hard to pin point.
F4U-1D 50% Fuel/Ammo -1061lbs
Gross weight= 11,114LBS
Mil power time to 20K= 7:31
Combat power to 20K= 6:38
Test method takeoff fuel burn=1 takeoff immediately retract gear level reach climb speed 150TAS MPH and hit auto climb start watch.
Here is the chart I am speaking of. It is from the manual. It is the second line from the bottom. It really is more than a 1 minute gain, it appears at that weight it should reach 20K in a hair over 7 minutes at mil power. Combat power should be over 1 minute better than that and it is not.