A couple of things strike me:
1. Did you use combat trim? If you did not, and he did, he may have been in a much better trim situation than you were. The higher you got, the more out of trim you may have been.
2. Auto climb is set at the best climb speed at sea level. The higher you went, the farther off your climb speed may have been from optimal. If he was climbing by hand he may have beat you.
This is all ignorant of what the performance of those planes should be in comparison to one another. I'll let those with more data fill in some of the blanks in that area.
However, if you think something may not be correct, I would advise you to do some timed climbing tests in both planes and report the results in the "Aircraft and Vehicles" forum. Generally folks there will have some real data to try to match your tests up with.
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Lephturn - Chief Trainer
A member of The Flying Pigs
http://www.flyingpigs.com "A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"