We are infrequent cruisers but, oddly, have done 2 this year. I think cruising is the only way to visit Norway: I really don't get this country at all- swimming in oil and gas, a small population, yet to eat and drink on restaurants costs you the national debt of a small country over the course of a holiday. e.g. At Geirnager we had 7 half pints of beer- i.e. 3.5 pints. Cost= �£50 (500Kr). Mad!
Anyway, here is my comparison: Boarding quick and efficient for both lines. Getting off equally painless. Restaurant food and service MUCH, MUCH better with Princess. (And no staff members begging us at the end to give them feedback as "excellent"!)
Princess has fresh water in the pools- a big plus I think.
B 422. Slightly less roomy that similar grade on RC. Despite proximity to lift- no noise.