After a bit of tracking down, if you find you are getting random crashes on Nexus 7 it could be this …
Look for any dynamically created images (e.g. CCLabelTTF) and check how big they are when you are displaying on the bigger, higher density, tablet. The Nexus 7 just crashes out over a certain size (without any hints of what went wrong).
Making sure they didn’t go over a certain size solved the problem for TeraGrid! Now the game is up and running without any problems on iOS and Android.