I've bought the $4.70 one several times. It is a good board with different mode groups available. The more expensive one (from the pictures) doesn't seem to have a microcontroller, so it *should* be a 1-mode 2.8A board (one of the reviews indicates it has modes, so either they are shipping something different or the review is for the wrong product). The second one may have a 2011 date, but the reviews go back to 2009.
I bought a few 5 packs (alot cheaper) and worked fine. I managed to kill one of the amc to get 350mA less draw for a comission speciality flashlight and the owner was happy for the added runtime and less heat and not much less output. At least not easily percieved drop in brightness.
On the newer version of this driver the 105c it kicks down to The lowest mode when the battery gets low. I am not sure if it starts to flash eventually but when mine kicks to low for the second or third time I change it out. I don't like to push my batteries and I always carry a spare battery so it might start flashing in low but I am not sure.
Hi guys i have a 105c i would like to make it a 3 mode, so by bridging star #2 from the right should be ok if ive read correct, im not a fan of flashy modes.