Benchmarking postgres on Solaris/Linux

As anyone done benchmarking tests with postgres running on solaris and linux
(redhat) assuming both environment has similar hardware, memory, processing
speed etc. By reading few posts here, i can see linux would outperform
solaris cause linux being very good at kernel caching than solaris which is
being the key performance booster for postgres. what is the preferred OS
for postgres deployment if given an option between linux and solaris. As
well as filesystem to be used (xfs, ufs, ext3...). Any pointer to source of
information is appreciated.

Thanks,
Stalin