Will a higher class SD card reduce the risk of crashing my Galaxy Ace?

I was using my class 4 32GB SD card in my Samsung Galaxy Ace quite happily until I filled it up to a certain point (which point, exactly I'm afraid I can't find out and don't know). Once the SD card reached a certain percentage of its capacity (Somewhere in the >20GB used area) it started going into the "Sleep of death" bug, where it cannot be woken up after going into lock. I then deleted some non-essential stuff, and the phone worked with the card quite happily for about 20 minutes, when the card died. I haven't been able to revive the card on my PC or phone. My theory is that the processor in the Ace couldn't handle that much data on such a low-speed card, which would explain the sleep of death, but not the card failure. Is there any merit in this idea? Would a better class 32GB card have a chance of avoiding the sleep of death, or am I indulging in some wishful thinking? Apparently the problem is very widespread in Galaxy Aces (according to the manager of a phoneshop I brought it in to), and it seems to happen the Nexus One aswell. Any thoughts would be much appreciated.