Well I already made a quick Video with my ACA1220, I didn't test my ACA1232 yet, but I will later.
[ Show youtube player ]
It's a really quick and basic Video, I've just prepped a CF with OS3.9 which I'm testing now and it runs great! There will be a new Video
Boot Rom is inside the ACA500 so yeah you should be fine loading 1.3rom/WB1.3 from a CF card, I will test this another time to see how the ACA500 fares on it's own with no ACA12xx
You can even boot from the AUX slot from a FAT formatted CF according to the manual.
Oh and I uploaded some more photo's to my gallery: