It only took like a couple months for his akedema to get soft. I was once considering buying one as well because I liked the reptilian series infield gloves due to the soft leather. I decided against the catcher's mitt because of his experience and a couple other people I have talked to about akedema.
Considering the breaking in question, IMO the only way to break in a glove is to play catch with it. I think that is the best way because you begin to develop a feel for it as well. The mitt masher is also not a bad idea. I wouldn't put it under the mattress or do rubber bands with a catcher's mitt. They are just too valuable in a game, and I like to get that feel as much as possible.