I don’t have the DX3B MKII, but have the DX3B, which has the same U/I, so a couple of thoughts. Like a lot of newer tactical lights that try to offer multiple modes, it is really a single mode flashlight for one hand use with the tail cap. That mode can be preprogrammed to either high or the next highest setting. If you want the flashlight to come on in any other mode, it requires two hand operation because you have to hold the side switch while activating the tail switch. For some, that may be beneficial if they want a multiple mode light with an absolute guarantee they can get high every time one handed and whichever mode they desire two handed at startup. Also, to cycle through the other modes, you have to use the side switch, while you still need to access the tail switch to turn the light off. For me, the one hand, two hand U/I didn’t work. I prefer the DX3B Mini Pro, which is side switch only, so single hand only needed to operate the light. Of course, the Mini Pro offers the XHP-50, not the XHP-70, which may or may not suit your purpose.