Yeah, I tend to prefer OT-ing in the towers, partly because of the constant aggro war between tanks and very few wanting to go for adds. Though sometimes I've run into epeen OTs trying to grab "my" adds as well as their own -- or worse, ignoring "their" adds. (Say I'm C tank, and handle the adds on the right side of the arena... and then the A tank runs over and grabs "my" add which i've already established aggro on, while ignoring the left side add going for healers or other squishies... If I'm B tank, I'll most likely pick the side of whichever party the MT is and grab those adds.)

Sometimes I've announced it as the start, like "dibs on OT" in alliance chat, especially if the other two are paladins, as that enables me to keep up debuffs on the main boss when there are no adds to handle. Other times I don't, and just go to position myself where I know adds will spawn soon. Sure, maybe I miss a GCD or few of damage on the main baddie, but at least I'll be in position and not have to chase the add(s) around XD

Of course, sometimes OTing isn't working, like when I manage to steal aggro with Defiance off >.< Or with Defiance on in preparation for adds, but while doing SP/SE combo instead of BB. Or when no other tank pulls at all, and we end up with impatient!dps pulling. (Or accident!pulling, like forgetting Foe's or forgetting their pet is on Sic and rightclicking on boss instead of leftclicking...)