I have found that most aircraft are not set correctly for maximum ft/min climb by default. Perhaps best climb angle alt/dist, but not best ft/min.
I agree 175 is near optimum for most planes. In the slower planes I'll go down to around 160 for best climb, and the faster ones up to about 200.
Never done any REAL testing, but after continuosly out-climbing my squadmates, we deduced that the default auto-climb is NOT the optimum setting in most planes.
g00b