Hiya Pyro!
Quite a long time now I've thought that the sustained climb rate of the 262 in AH seems to be too slow. I wondered this since the weight increase in April 2004 during the AII beta, actually. According to the J. Richard Smith's and Eddie J. Creek's authorative study on the Me 262, "Me 262's" second volume's (ISBN 0 9526867 32) appendix seven (p.442) the 262's climb speed at sea level is 19.3 m/s (3798 ft/min). They don't seem to mention an exact source for this info but I assume it's from Messeschmitt's own testing.
Below is a primary source test flight document that seems to agree with Smith and Creek:

Two climb curves can be seen. It is pretty hard to make out what exactly is written about the left most curve but for the right most curve it seems to read "Erflogene Werte" which can be loosely translated into "test flown figures" or "reached values". Again, it's hard to make out what is said on the left but in the context of the right curve it looks like it could say "Rechnen Werte" or something similar which roughly means "calculated figures".
Below, I've plotted two additional climb curves into original HTC climb chart for the Me 262:
Green curve is from my tests in AHII. Me 262 with full fuel and ammo currently weighs 7115 kg (15685 lbs) in AHII. Green curve is based on a test I made using 1.0 fuel multiplyer. I took off, accelerated near the best climb speed (~290 mph) on the deck and burned enough fuel to reach 7000 kg (Test weight listed in the orig. document I posted.) and hit alt x. It takes roughly 4000ft for the autopilot to stop oscillating. After that accurate climb rate can be observed using E6B. I took screenshots every 4k and plotted the above curve. As climb rate below 4k is very difficult to measure accurately I just drew a line with a same slope as the upper curve to 0 ft since the decrease of the climb rate is linear in AHII.
Red curve is "the flight tested figures-curve" from the primary source document.
Black curve shows what the climb rate was in AH1 with full weight (100% fuel/ammo) before the weight increase. HTC still displays this curve and the original weight on the planes, vehicles & boats -section. I haven't tested if this curve is still accurate for the original, lower weight.
So it seems that Me 262's initial climb rate in AHII is roughly 450ft/min slower than what the flight test on 1.12.1944 shows.
Pyro,
I hope you view this information and take a look on the Me 262 in AH. There are lot of discrepancies between different sources when it comes to the weight of this aircraft. For example according to Smith and Creek lists the empty weight of the aircraft as 4120 kg (9083 lbs) in AH the empty weight (with the pilot, of course) is 4814 kg (10613 lbs) currently.
Thank you for listening!

Others,
(I wish I would not have to add this but I also know the nature of this forum.)
Please keep this thread civil and on topic. I am very interested about everything that might have relevance to this issue. This, for example includes, primary source weight documentation of this aircraft (ladeplan-documents, etc.). What I'm not interested in are off topic comments that don't contribute anything to the topic or useless speculation which isn't backed up with any form of documentation. For example I couldn't care less how good/bad you do in 262 in the game and how the climb rate should/shouldn't be changed because of that. It has nothing to do with the topic in hand.