I almost always take BIA, but fully-aimed accuracy is really important to me.
T29s can be really tough, but mostly just when they are in great cover and not distracted at all. If they're in a good position and see you first either try another approach or back off until they look away, then pop them. Except the front of the turret, everything on the t29 is quite weak so just hit what is convenient. If the turret is still facing you when you are taking the shot, try to hit the top of the front hull. Most drivers leave at least a sliver of hull exposed, and with the Tiger's accuracy you can often hit that sliver. You can also try the commander's hatch, but you really need to be looking down on them for that. Of course, the best thing is to catch them out of position, but that really makes short work of almost anything. But, the t29's rof is pretty slow so if you catch them by surprise you can normally get in a shot, absorb dodge or bounce their first shot, fire again, and escape to cover before they've reloaded for a second shot.
Afaik, the only thing that really works on brit TDs is teamwork. They all have some weak points, but they are still bitches to kill in 1v1.