I tested the D25 and D30 offline, both 100% fuel, 8-gun, 267rpg. D25 wep climb matched the help charts at 2-3000ft (~2900fpm). D30 was exactly the same as the 25, not the ~3200fpm in the charts.
I could get 3250fpm out of the D30 by taking 50% fuel, but the same goes for the D25.
Unless the charts are for different fuel/ammo loads it seems something is amiss.