I have a CLF that recently completed her HRCH title (7 straight passes) and has her SH (5 for 5). I plan on running Master in the fall. What are the major differences between Finished and Master that I need to prepare for? Any advice appreciated.
Going 7 for 7 in Finished and 5 for 5 in Senior, you should be in pretty good shape. Note that there are far more similarities than there are differences between Finished and Master. That said, the biggest differences are:
(a) No talking to the dog on the line after you call for the birds (you should be used to this as you have run Senior).
(b) wait to send your dog until after the judge calls your number (again, same as in Senior).
(c) Master marks tend to be tighter, and you are far more likely to see things "interrupt" the marks. Ie. a diversion after 1st bird, have to run the blind first after seeing the marks, etc.
(d) HRC has a philosophy of "it's ok to handle on a mark if the dog is hunting the area of the fall". You could conceivably handle on all 6 marks in an HRC finished test and still pass. AKC does not follow this philosophy ... unless circumstances are really odd, you pretty much only get to handle on 1 mark for the entire test.