I have done some testing with my pieces this weekend.
Mine were delivered with V4.4 installed, and I upgraded one of them to V4.6 using the scsi2sd util.
Testing on an A590 controller with Guru ROM, theres a noticable difference in speed for the 2 releases. I get 1900KB/s using V4.4 and 1200KB/s using V4.6.
Speeds are measured using the same SD card (setup for 2GB partition) in both units.
Both adapters are using a 32G SD card. With V4.4 it is possible to read the settings with scsi2sd util, but not save it. Then I get an error messave, and this in the log:
16:18:26: Saving configuration
16:18:26: Programming flash array 1 row 187
16:18:26: Error writing flash 1/187
16:18:26: Save failed
With V4.6 I succeded to change the settings (changing SD card size to 30GB).
I also did some tests with boot time.
Using my main A500+/A590 system (68HC000 @28 MHz) I get the following results:
Kingspec SSD + Acard IDE-SCSI adapter: 7.2s (RSCP transfer speed 3200KB/s)
Compaq 10000 rpm wide SCSI disk: 7.5s (RSCP transfer speed 2200KB/s)
SCSI2SD with V4.4: 7.6s (RSCP transfer speed 1900KB/s)
SCSI2SD with V4.6: 7.7s (RSCP transfer speed 1200KB/s)
Further boot tests on A500 test system (A590 with Guru & speedgeek hack) with the same boot partition (68HC000 @ 50MHz):
Compaq 10000 rpm wide SCSI disk: 4.8s
SCSI2SD with V4.4: 5.3s
So, while they appear to work quite good, theres an unresolved issue there. I would like to have V4.4 on both units, but with only 2GB available it is unusable.