Higher capacity and lower recoil. A full powered shotshell is a handful out of the wee beast. I can't remember where I purchased a Magpul forend that had been modified to work with the Mossberg, mounted a laser aiming device, into a scabbard and into the trunk of my crappy old car that I run around in during the winter when I put my nice townie away.
Also, I've been less than impressed with Remington's quality the last few years.