I run the Stak case. I searched for a used Atlas before this and it was hard as hell to find one in my price range of 1500-1900. They can be had for that price but for me it just wasn't worth it plus the size difference makes it very difficult to slam in a TJ with a flat belly.
I would run the 300 as is and see if you break it. They are strong cases and get a bad rap from people that manage to break them. Honestly, it sounds like the same people that break them have some type of drivetrain stress beyond the normal amount. There is no reason to spit a case in half unless the entire drivetrain is bound up. In that case, the driver should recognize this and take off the stress in the system. Again, it's not everyone that breaks a case, most people will break an output with more power and bigger tires. I will ask this question: why is it that the people that break cases keep breaking the actual case instead of the outputs? Completely stock case and internals yet the case breaks multiple times...think about it.
I will say that the Stak case makes changing outputs a breeze. You can do it with the case still in the rig! Much easier and much stronger. Plus you get the option of driver drop. I just picked up a complete set of stock outputs and gears for $80 :smokin: