David,
Which workshop of Sexton's will you be attending? As I recall from his latest brochure there were several offered. I think that John is probably one of the best printers out there today. I base this on what I have seen of his prints and from what I have heard of his masking and retouching of negatives. He seems to be a lot more technical in his approach then the other workshop that you attended. I will be interested in hearing of your experience. Good luck.