I too am booked on the Diamond and for now I am going to leave the booking alone. I don't sail until Aug 3rd, but have booked the Amsterdam for Aug 2nd as a backup. I have not sailed the Star Princess and have not been impressed by the recent reviews of people that have sailed her. The pricing on HAL is high and I have a standard outside cabin on her, while I have a suite booked on the Diamond for $ 200.00 more.
I guess my real concern is not over the saftey issue of the Diamond, but if the Grand class of ship on Princess is just too big for me. I like ships in the 70-80,000 ton range.
I am a person who does not think that "bigger ships" are better.