Well done on all this Paul.
Your end results have surprised me. For as I think I've said before, most x-ray work I have seen from others has been quite contrasty and lacking in tones. Yours seem to have a good range of tones and as you say, loading one negative at a time in your Rollei, along with an ISO of 25, will definitely slow you down a bit.
One question that comes to mind is, what type of lighting were your shots taken under? Was it sunny day or cloudy and diffused light etc.
Terry S