This question belongs in the Lights and Lasers forum, not here.
But at anyrate, there is no practical difference in distance. All civilian lasers are limited to 5mW and then it's a matter of focus, dot size, color, and pattern (blinking or not blinking). Both the Surefire and OTAL will actually project a dot for more than a mile (in the dark), far past any useful range. The Surefire is nice if you want the modularity and swapablity with the rest of your Surefire gear, but the OTAL has a superior package. Some don't like the offset of the OTAL though.
Forget using any laser in bright daylight. I can't see my SF L72 past 10 yards in the bright daylight. It's possible on the right surface, but you would have to already know where to look and look HARD. They are generally limited to less than full daylight conditions, dark or darkened areas, the conditions where a real encounter is likely to happen.
Get the OTAL.