I hadn't thought of this when I first got intervene and didn't have the ability to charge in combat. The only exception I have for this is as prot in defensive stance I have intervene bound to my charge key and have to hold shift to charge.
Like on my warrior my taunt is always the same button regardless of spec. If a spell is always available regardless of spec I try and always keep it bound to the same thing. My suggestion though is try to keep things pretty universal when you can when it comes to keybinding. idk, its just how i'm used to seeing them.I was actually going to guess that was the probably part of the issue with simply moving the keys, but didn't want to assume you were transitioning to keybinds since you are asking for help with binds. The occasions that i switch to ret i have to deal with spells in a different position. I just switched from clicker to keybinder this week and the way my spells are positioned its easy to see what i just clicked and stuff in tanking spec (which i'm in 95% of the time).