How reliable are IO timing statistics in v$filestat/x$kcfio in Oracle 9.2

Hi All,
I am gathering some data on the amount of time that Oracle took to read and write (IO statistics). I am using v$filestat/x$kcfio for this purpose. I would like to know how reliable are the READTIM, WRITETIM, AVGIOTIM, MINIOTIM, MAXIORTM, and MAXIOWTM statistics. Here is what I am trying to achieve. I am in the process of implementing ODM (Oracle Disk Manager, from Veritas) in my lab. We are running Solaris 2.8 and Oracle 9.2.0.4 (64-bit). Since ODM offers RAW like performance features, my goal is to run tests as described below:
-- Run a test with the buffered filesystem first and collect IO
statistics then
-- Enable ODM, increase the SGA size to ensure that what was cached in
the filesystem buffer cache can now be cached in the SGA. Run the above test again, collect the IO statistics and then compare to see the improvement/degradation.
Is there a better way to gather IO statistics (sar, iostat), etc than from v$filestat/x$kcfio ?

Any help will be appreciated

Thanks
Amir

--
http://www.freelists.org/webpage/oracle-l