GRP
The Indians book may be quoting full power on both a/c, whereas climb power for the Archer is full throttle (therefore full power) and the Arrow is 25/2500, less than full power - so not eggs and eggs.
I agree that 500fpm is about right for the Arrow at climb power and the Archer at the same weight will give about 800fpm - but full tanks on the Archer (50 US gals) and my family, is less than gross.
Also, if you find a turbo Arrow with the continental engine, the climb rate is better, especially if the density altitude is high.