Might I suggest that you read up on RAID arrays and what they do?

ANY RAID configuration is going to be slower than a single disk system. Even RAID 0 will be slower.

In the environment you describe I would say that RAID 0 would be little short of suicidal. lose one disk and you have lost the lot, and it won't be economically recoverable.

I have an idea that might be of interest to you. You can get software to make an image of your HDD. This could be user driven or scheduled, or both. Maybe if the guy did this when he went to lunch and when he went home he would only have half a days work at risk.

I presume that most of the production work gets saved to a server when he finishes working with it? so he may not even risk losing that much?

Incidentally, if you remove one of the mirrored drives the system should revert to being a single drive setup and run much faster