You might be able to break it if it is truly RAID1, but I would think you'd need to run a repair to get it booting again. But, we can back up a step. Why bother with RAID at all? It's wasted on a single user desktop, especially for mirroring. It isn't a good backup method, so why use it?
If it was my system, I'd run one drive internally, cut into C and D partitions, then stick the other drive in an external housing to use as a backup drive. No need to overcomplicate a system setup, and no need to mess with dynamic drives.