The technique I used with this image was to play with the layer blending options. I stacked the 3 exposures with the brightest on the bottom and the darkest on top, and then played with the blending properties. (Right-click on the layer, and select Blending Options from the menu that pops up.) By holding down the ALT key and dragging the black slider on "This Layer" (which will split it in half) I made the darkest areas of the 2 upper layers transparent, causing the brighter areas of the underlying layers to show through. I spent about 10 minutes twiddling the sliders around before I got a blend I liked, then flattened and saved. No airbrushing layer masks involved. The result speaks for itself.