I can't think of anyone here who has done an early debarkation on a transatlantic cruise.
The Radiance-class ships are perhaps the most loved among Royal Caribbean loyalists. They are often considered to be 'just the right balance' being not too big, not too small, and having lots of public areas. This is good for a transatlantic since you will have many sea days which can get boring to some cruisers.
I don't know your ages but you obviously lead an physically active lifestyle. Be aware that cruises of this length often have an older passenger demographic, and it is also likely that many of them will be Royal Caribbean loyalty members. In other words it will be a cruise-savvy crowd for the most part.
I've never cruised on a transatlantic, but I did spend a lot of time in the north Atlantic while in the Navy and crossed the Atlantic 4 times while aboard both a cruiser and an aircraft carrier. The weather is notoriously unpredictable. As for pool time...the Solarium is covered and always an option if it is too cool or windy for the outside pool areas. Wind is perhaps the most common weather issue for the Atlantic, especially in the spring and fall when cold fronts are more prevalent in the northern hemisphere and sweep across the sea from west to east.