I've had some success backcapping IBT and TP. It is a pain running up those towers, and fighting in them, but I can usually win. It's usually 2-3 sub-80 toons in there which die real nice.

pro-tip: you can drop totems on the last level before the top and they will still reach you...this way you are prepared to go right to battle when you entire the flag area.

Also, beware of elemental shaman, they will TS you right off the tower (which I'm sure we all know from personal experience). I always tab through the enemies before I go in to see if one's in there. If so, you gotta juke around and get them to blow that first.