Probably worth noting that the various newer environments published in the development forum all do in fact already have a separate boot partition. At least in the case of Arch, Gentoo and Bubbagen this boots an interstitial kernel that allows you to pass any command line parameter you like to the actual kernel and you would not have to change anything in the u-boot environment to run from RAID.
I should probably be more specific about my objections to using RAID at home. RAID was originally developped as a poor man's alternative for extremely expensive durable disks. The idea is that by storing the same data on multiple much cheaper disks you can correct read-back errors on one disk by fetching the failing data from the other disk (in case of RAID-1, it gets more complex with other RAID setups). The thing here is: you need to actually monitor the system or you may only notice the problem when the second disk starts to fail as well. If someone pays you to do so, sure. But who does this at home? Here's the second problem with RAID: when you setup a new system you are likely to get two identical disks from the same supplier, the same manufacturer and quite possibly with sequential serial numbers. That means that because the disks will be stressed equally throughout their lifespan they are very likely to fail around the same time, which can be hours or even literally seconds. Don't laugh, I've actually seen that happen at a customer site and because they had put too much trust in the false sense of security it turned out they did not actually have a complete backup of their vital data. Thus here's the most important thing about RAID: it does not eliminate the need to make backups.