I have found that the 9C staterooms are cheaper than the secret porthole rooms. I have been in the better of the secret porthole rooms and it was obstructed enough that if I could get a 9C for the same price or less then I would go with the 9C.
Similar for me, so I definitely recommend to check some of the cat9's before automatically assuming the "best deal" is the secret 10a. I was paranoid about booking on deck 2 because of some of the public areas & was concerned about noise from above on Deck 3 (like the Wavebands nightclub on Wonder), so check deck2 room location carefully. I'll be in my first deck2 cat 9b cabin in November and look forward to it!