I guess I haven't been out in a really heavy rainstorm, but a little while back I had to check out some leaks during one of our larger northern CA storms. My surge did a pretty good job, but I would have liked even more beam "spread" for what I was trying to do. I tried my Tec40, and it just didn't compare, as the smaller and less powerful beam tended to get swallowed up by the drops. (I don't even know if that makes sense. When I look at the two beams under normal conditions, they look surprisingly similar (I overdrive a 3-cell lamp in the Tec40), so I was surprised at the rain-based difference.)
I don't have a SL6, but from what I've read here, it sounds like it would have been a good light source. I just wonder if I could have handled the extra weight as easily while climbing up and down ladders. Carrying both the Surge and Tec40 was no problem.
John