We have changed resorts on almost all of our trips. We have stayed in as many as three different resorts on one extended trip two summers ago. We started at the Beach Club, did Contemporary, then to Boardwalk. Each switch was a breeze. Bell services took care of everything, even what needed to be refrigerated! You have to be in your room for them to take your stuff, and in your new resort room before they will drop it off. (Its not like the magical express when they just drop it in your room for you). Its very easy to do. We are doing it again this summer (Riverside Princess rooms to AKL). Its a great way to see so many of the great resorts Disney has!
The only time we had an issue was switching from The Swan to WL. Our stuff was moved by the Swan staff to AKL. It took over 2 hours to find our stuff and the staff at WL, NOT Swan, did all the work to locate it and get it. They even drove us in one of their vehicles to the entrance of Epcot because we were running late for our diner reservation. The Swan did comp. us for 2 hours at the kids club in WL (don't recall the name) so my wife an I could sort it all out. But only after the WL staff suggested it so the kids didn't have to sit in the lobby the entire time.
Other than that, the its been a breeze. Have fun!!:wave: