The BIOS/Firmware version that you are using is very old. There have been 2 new versions that fix many problems and increase the performance. I recommend you reevaluate your review.

I have to say that I also would like you to retest the ASR-5805 as there have been 3 newer bios releases with a lot of fixes but also performance improvements. I would very much like to know how much the write performance has been improved as it was really bad with the firmware you used.
From the release notes of all 3 newer bios version I copied the performance updates:
16343 (8 Dec 2008): Improved linear read/write performance scaling for RAID5 and RAID6 configurations
16501 (18 Feb 2009): Increased RAID1 and RAID10 performance
17380 (24 Jun 2009): Enhanced RAID-5 Degraded Mode Operations

As the new 5 series Z controllers with SuperCap instead of Battery use exactly the same raid engine and use the same firmware the reevaluation of one of 5 series with 8 ports would give us the info of the whole family including the current models

I do appreciate all extensive reviews you do for the raid controllers and all the time you have to put in it. Almost no one else reviews these controllers regularly and extensivly, so you are my only hope