After our experience recently in a Cat 3 room, I'm not sure I would ever stay in a Cat 4 unless it was under the part of Topsiders/Beach Blanket that is carpeted. We were in 8048, which is just about the middle of the ship and every night we were awakened by CMs rearranging the deck furniture above us on deck 9. They were dragging the tables and chairs back into place, and made a lot of noise on the wooden deck. Also, the night of the deck party, I would think that all of the rooms in the middle of deck 8 would be very noisey ( I know ours was).
If we go again, I would love to have a Cat 3, but...... would probably opt for a Cat 5 or 6 just to get some peace and quiet at night.