Every crash cymbal I've ever cracked in 35 years has either been a cheaper B8 cymbal, or a heavier cymbal. Cheap B8 cymbals are brittle and don't have the ability to ripple and flex, which leads to breakage. Thinner cymbals speak more quickly and flex more on the hit, so they are better at distributing force along their entire body. Also, if the cymbals are being mounted too tightly on the stand, or at too much of an angle, the force of a hit can't be fully distributed and makes it more likely it will crack. Finally, consider how the cymbal is being hit, and where it's positioned. If the hit is going through the cymbal instead of along or across the cymbal, it's more likely that it won't be able to take the hits over time.
Smaller cymbals have higher pitches, but they don't displace enough air to project in the same way that larger ones do. You're probably more likely to break a smaller cymbal by getting it to do something it physically can't do, which is beat a guitar stack.
I get the wanting lots of volume thing - it feels great and it would probably actually kill your guitarist to turn down. In which case, you probably need to be miked up. Drums and cymbals by themselves can never compete with a Marshall half-stack at 11, especially in a small, enclosed space. An added benefit of miking up is that you can use in-ear monitors to hear yourself at a comfortable volume, which means you never overplay your gear competing with a guitar. And here's the other thing - the stage volume is never what the crowd hears unless they are standing on stage with you. The real sound is in front-of-house. Overloud stage volume turns into mud and is difficult to separate into a listenable mix.
Even if you're just garage banding it for now, there's no reason to consistently play at 11. It's hard on gear, makes enemies of your neighbors, and kills everyone's hearing. I recognize that's not a battle that can be won in every case, but I firmly believe it. It's one thing to be breaking cymbals when touring arenas. It's quite another to be breaking cymbals playing in a a garage - an expensive thing.
