If you break the firing pin in a Mini-30, you very well may have to ship the whole rifle back to Ruger to have it fixed.
Change that to you will definitely have to ship the rifle back to Ruger to have it fixed. Firing pins for the Minis are a Ruger only part, they will not sell them to anyone else, the reason being they need to be fit to the bolt. The only aftermarket pins that I know of are the Glend Arms pins which also have a reputation for breakage, something to do with how they are heat treated I think.
Question at hand is whether the M1A is worth the extra money, depends on what you plan to do with it. In my opinion The M1A is absolutely worth the extra money. I do not own an M1A yet but I have fired them and I love the rifle and plan to won one just as soon as I can justify spending that much money. If you plan to keep all your shots at 200yds or under then the Mini-30 may very well be the rifle for you but if you want a little more punch than the 7.62x39 can provide then the M1A is your rifle.