I think it's great you are doing something different. What I will say is that for many jobs or contracts I have had, the performance report given in the middle would be extremely positive, but then at the end when we had a disagreement or I had decided there was a better opportunity, it would be negative because I was giving them extra work to replace me. I am sure I am not the only one.

So I think that you may have trouble getting really objective evaluations of performance.