I've got about 135K miles on my 9-4x and had to put in a new battery this week. I bought one at Costco and had no problems with the install. All my radio stations stayed the same, and the air pressure reading on each tire took about 5 minutes to restore. I didn't loose the automatic up and down of the window on one-touch, and has not discovered any other problems. While the battery looks pretty complicated that change only took a couple of sockets (a 13 & 10, I believe) and about 25 minutes or so. The new battery at Costco was about $115 and was exactly the same size.

Slow starting and then not starting was the signal for a new battery in my case.