Dell 2950 with SAS - switching to SATA possible?

I have a Dell 2950 with SAS disks installed from Dell. I want to
replace the SAS disks with Seagate 1.5TB SATA disks. I've read
conflicting info regarding the need for a special "interposer" board
which sits between the SATA disks and the SAS backplane:

http://www.lelong.com.my/dell-powere...-06-Sale-P.htm

Most posts say it isn't necessary:

http://en.community.dell.com/support.../19695227.aspx

http://www.baasaa.info/20110409/dell...r-sata-drives/


But other posts say it is (or might be?) required:

http://en.community.dell.com/support....aspx#18586627

http://en.community.dell.com/support.../18742269.aspx

Does anyone know what the deal is with this interpose board? Does it
perhaps add some extra performance that I wouldn't get by plugging the
SATA directly into the backplane?

I plugged the 6 SATA disks directly into the system, built a RAID5 in
the PERC utility, and had no issues. But I would rather not have
everything fail in the near future due to some necessary piece of
hardware.

Any help would be great.

Thanks!