As an update here, I talk to the Bru folk and got a lot of great info. I plan to get the PE when it's available. Hopefully it will be available soon before the order goes through to save me grief of a second PO through IT.
I also talked with ATTO, and my solution sounds good. The only hitch is my MacPro doesn't have enough PCIe juice to run both the ATTO (8x) and HighPoint eSATA (4x) with my Graphics (16x) at full speed. Do you think there is a speed difference on the LTO-4 between 4x and 8x? I'm wondering if I'd be better off just using the ATTO and just get a 4x eSATA fan cable on the second port for my eSATA RAID-0. I likely won't be using that take drive during production, but I will be going from the eSATA drives to the tape drive.