Just a test, I went out trying to get it before dark because really for night lightning i would be using photo mode to take bulb mode high res raw stills. But for a evening sky where it is still to bright to do long exposure for night lightning I went to test the sensitivty of the trigger.
My test setup was using a a/c external flash bulb from 70 feet away and my first test was with scanline set to 1, it did not pick anything up, so I went to 20 scan lines, then it created a huge spike on the graph. So I went down by 5 and success till I went below 5 scan lines and the spike was smaller and smaller the less scan lines I used.
So if it can pick up the little light, it should easily pick up a lightning bolt even on a lighter grey storm sky, the darker the sky of coarse the more likely it will work.
Are only issue will be the rolling shutter cutting the images in half, but I found using a strobe light I tested the best fps and shutter speed to have greater success to reduce the gap between the scan line plus have more full frame captures without cut off.
My best success was set camera to 1920x1080 30p mode in Canon menu, then in ML turn on fps hack and set to EXACT at 15fps, then use exposure override to set shutter to 1/15, this will make the cut off line as skinny as possible which maybe allow for merging the cut offs together, because when setting the fps to 15 it seems to capture any cut in half images on 2 differ frames so you can merge them and make a full frame out of them. Plus setting to 15fps also captured more strobe flashes within a certain amount of frames as well.
Any lower then 15fps you risk the sky washing over the flash cause day skies are bright, so you dont want to long of a shutter plus the slower the fps and shutter the less the bolt trigger works. But to fast of fps and shutter the less flashes you will capture and the more cut in half images you will end up with.
1280x720x60P canon mode works as well, but not at a shutter of 1/60, it misses a lot of flashes, not the trigger, just the live view, the trigger works well in all my tests except long exposure, so avoid them.
If you go 60p mode then set fps to 30 or 15 and adjust shutter to 1/15 or 1/30 depending on what fps you go with, both work fine.
But on T2i when in 1280x720 mode, whether your taking a MOV or using Raw, this cam has banding issues and antialias issues plus I like using 5x mode to get 2512x1080 res. I can achieve this because I just have the bolt trigger capture 1 post frame, so just in case the bolt gets cut in half the main detection frame will be caught on the first frame and the other half will be on the post frame, would be cool to get 1 pre frame when the module gets set up for pre buffer capture if it is possible just in case a half for some reason gets caught on the frame before the detection.
Well, these are my findings from my tests just to get this thread started
By the way, I live in the US in Florida, so I am in the heart of lightning season, expecting action any day now.
I have been a lightning photographer for 10 years now.