the problem with that is when your boot drive dies your can't boot...with ubuntu at least if any drive dies i can stilll boot off of the other 3..:)
You don't need a boot drive, you only need a *boot partition*.
So, you create a small *boot partition* with RAID1 and then allocate the rest of your drives to a RAID10 array.
You will still have redundancy (RAID1) on your boot partition.