MacBook Pro - Express34 cards for 2009 late Unibody 17" Macbook Pro (MBP)

I am running snow leopard 10.6.1 on my 17" unibody late 2009 MBP with 8gb RAM and a seagate internal 7200rpm drive.

since i do HD videos mainly with my MBP using both Final Cut Pro and iMovie09, storage has been my major concern.

i now use a Drobo 800 and 3 other external enclosures with firewire 800 connections. namely 2 icydocks and a cavelry case.
with testing, i am getting up to 32mb/s write on these external firewire 800 drives.

the strange thing is that i am also getting about 30 to even 34 mb/s with some external USB2 drives. this struck me as being odd as i would think the io with firewire 800 drives should be faster than USB2.

then i tested the internal seagate and that too was about 30 to 33 mb/s in write speed.

so, finally i bought a couple of eSATA express34 cards and a couple of external docks with SATA connections.

with the ioGear express34 card and an external seagate 1.5gb 5900rpm drive, i got 64 mb/s with even large batches of files up to 15gb. this is far more than my 8gb ram, so i don't think anything got cached.

next, i tested with the Sonnet Tempo SATA Express34 card and only got 50 to 52 mb/s of write speeds.
that is a lot of difference between the 2 express34 cards.

i used SIIG's 3132 Mac drivers with these tests.

anyone with similar experience out there?