All good points. The range is a combination of IR LED Power, IR Sensor sensitivity, IR Sensor filtering, and ambient conditions.

The IR LED is one of the better ones I could find with suitable power and angle of spread. I did get better results with the Radio Shack LED that's frequently quoted as a Tamiya replacement, but can't get them in bulk for a decent price. Note that variable power may be explained by the gauge of wire you use...too thin a wire and the resistance will reduce the voltage the LED sees.
An IR Laser would be neat for sniping, but I suspect that aiming would be hard without a video camera and display, and at short range the lack of spread would let other tanks eat you alive!!! YHR may experience the same thing with his lens, but it would depend on how focused it got.

The IR Sensor sensitivity seemed to be decently comparable, but of course that depends on the housing and filtering you apply.

Naturally, if you were a hardcore competitor, you could hookup a TBU and the Tamiya LED to a DBC instead of the DBU. You might need to add a resistor inline and tweak it for equitable range though.

I'll be interested to hear what the results on the upcoming battles are. Pity I can't join in!
Hrmm...perhaps if I hooked a tank up with a camera and a wireless internet connection.......

Cheers,
David