ANSI throw I assume? Single reflector will out throw a triple reflector of the same width, but the WT1M has a bigger head to maximize throw, while the WT3M is more for flood, so size isn't as important. The WT3M even has an OP reflector to soften the hot spot and make a more uniform beam, and with the 3 reflectors it doesn't need depth so overall, the WT3M has a smaller head.
I just ordered a WT1M w/XHP50.2, silver of course...