Ah, I probably should have qualified the issue
The install isn't hanging, it's working fine using Niresh kernel v2.3, it's running as my day-to-day server now but there's still a large amount of opemu errors coming through. Once the network driver must have crash as well or something because it was flooding the logs with messages about having run out of available frame segments. I had a nose at the source for that one and decided to adjust my MTU slightly. That hasn't happened since but I'm keeping an eye on it.
When I tried the BSA kernel I can't really remember where the boot got but I had tried all of those flags (all but the -f are in my boot plist anyway) and the kernel was already called 'mach_kernel'. Not sure at the moment what to do. I'm very tempted to buy a baseline Mac mini but the cost of a decent thunderbolt attached storage array is just insane!