Judy, While we liked the Voyager better than the Diamond, we felt that the Radisson experience was the same on the Diamond as on the Voyager.
The rooms were, of course, not as nice as the Voyager, but few are. They were nice though. I was unhappy with the 7th floor front rooms and would not take a room here. I also think that there were maintenance problems with rooms on that floor.
I would choose a balcony suite on the 9th floor in the center or rear of the ship and not in the front near the anchor. I agree that the dining room is superb (food and ambience) and the service levels are VERY high: maybe the best that I have experienced on any of the ships.
The showroom was also lovely, but small, so shows were more scaled down. Since it is smaller, everything is scaled down. However, the ship is very elegant.
Is the Diamond cheaper than the Voyager? If so, perhaps you can take your compensation and apply it to the Diamond. Captain Neil is delightful and you should have a nice time. We did.
If it screws up your back to back, I understand your frustration. However, remember my main complaint was TIME OF YEAR. I was told that October is the rainy season and we found much begins to close on the Greek Isles at this time of year and the weather is iffy. Perhaps you can take a September cruise?
Not to be hypocritical...we booked a cruise next November and chose the Voyager (we could have chosen the Diamond). The costs were $1000 less for a non-balcony on the Diamond for the week, but we would have had to travel San Juan to San Juan and we prefer going in and out of Florida. By the time you upgraded to a balcony and figured the additional airfare for San Juan vs Fla and San Juan hotel costs, it was cheaper to do the Voyager.