I have a T4 and don't believe you can use regular lithiums with it. It is probably not a good choice for trail use as it may not be as water resistant as say the T3. I was using an Inova XO3 for my backback but just picked up a Surefire L2 to replace it.

The L2 beam seems to be a cross between a spot and a flood. Oh so bright but probably not as good a throw as the T4 or Streamlight TL2. All three are rated at 100 lumens. For trail use, consider the Surefire L2. Two brightness levels and long battery life.