I also tried a V11R and decided to stop using it because it cannot hold constant brightness. After I let go of the control ring, the brightness keeps changing, up or down, without any input on my part.
I then did a test to see if it was responding to the Earths Magnetic field, and Imo it IS
I can make the light change brightness simply by turning the whole light to a different position. There is absolutely Zero regulation to the V11R, and I had to constantly keep changing the position of the control ring, to try and keep the output constant.
watch this video, you might understand better:
and just so you can see a control light, to demonstrate regulated output compared to the V11r, watch this
Bottom line, if constant output after selecting the desired brightness is a goal, the V11R is a FAIL