Actually, thinking of it, no one ever told me that you shouldn't be tuning 12 strings to concert pitch. Everyone that I know does it- even the ones I thought they knew a lot of things about guitar. My english teacher for instance-an amazing jazz/ blues guitarist who used to play pro- I always jam with him every after class back in my highschool days and he has noticed the little bow in my guitar but he just told me to have it checked. My luthier back then, when I used to live in scarborough, never mentioned about it. Even my good friend who plays the lead guitar in our band (before he got his hand into an accident) always tunes his yamaha 12 strings to concert pitch and he never gets any problems with it. In fact, his 12 string has outlasted his 6 string. He's the most careful guy when it comes to guitars but somehow, the bridge just popped out from his 6 string. It's good its covered by the warranty so he is getting a new one soon. The only person who told me not to tune my 12 strings into concert pitch besides you is my current luthier who has done the mods in my main guitar but he gave me this advice when all was already too late- the neck was already beyond repair. But I guess I've learned my lesson. Right now I'm just thinking about my korg ax 1500g so that i can cope with my loss.