mdadm only supports intel raid. the problem is that the default name is Volume0, this name does not really work well. If you create intel raid then use a name without a number at the end and it will work fine to boot from (in the case you use raid 0, if you use 1 or 5 then it will only boot after it has been synced). dmraid has the main problem now that it does not support gpt at all, that means you can access gpt partitions not in the initrd, if you call partprobe (from parted) later then gpt partitions will appear as well but by default you only see mbr ones. i patched gparted (newer versions should not need that patch) to be able to format fat partitions on md devices for uefi boot, thats no problem at all. you can directly boot from uefi as well via mdadm but you always need an initrd. i tested that long ago, but ubuntu is always late
I'm ignorant. I thought mdadm was purely software and doesn't care about things like intel raid hardware?