I had a chance to fly yesterday evening with these strobes during pre-dusk, dusk, and after dark. The sky conditions were a high, broken to overcast cloud cover. I used a P4 with two red strobes facing forward in front via Aerial-Pixel's Version 2 mounts, and two white strobes mounted in the rear facing backwards, all four strobes mounted low on the gear legs.
During the pre-dusk (still daylight but sun low to the west) I could definitely see the white further out versus the red. I could see the white clearly out to 2500'. As others have said however, if I had not been watching it heading outbound the entire time, I probably would not have been able to quickly spot it at that distance if I had looked away. On the return, I was able to pick up the Red at 1000'. I then reversed the copter outbound with the red facing me, and lost the red at 1600'.
During dusk and after dark, that is where they really shine. I could see both the red and white as far as I felt comfortable flying based on my battery. On a clear and low-humidity night (which it was), I would say that these little strobes are visible for three miles. They truly are amazingly bright for their size.
Regarding any affect on the camera, after dark, I did notice a very, very slight red 'ghosting' on the outer edges of my iPad's camera image. I did not notice this during daylight or dusk, but obviously, it was there. After landing and taking a closer look, I noticed that the mount itself transfers light to the sides via the whole mount glowing briefly with each flash of the strobe. I think if the mount was not there, there would have been no 'leak' of the strobe's light sideways, since these things are like laser beams. So, I am wondering if these mounts could be made out of a black material that would block sideways transfer.