It's just a push of the button to go between high and low beam, but you need to set it up when you first get the lights with I think its a five second press of the on button, although I can't quite remember exactly. The lights are pointed down a tad, so they don't shine into other peoples eyes too much. They've saved me from hitting Badgers and an Elk, so I'm happy using them despite the extra bit of weight.
I changed the thumb screw on the bracket to an allen head screw and as the lights are mounted either side of the stem with the Garmin in-between I can't really move them to one side. I do the hand over the light thing as a gesture to oncoming vehicles to show that I've dipped my light and expect them to do the same. It's no big deal to do with one hand.
I'll be using both at the weekend on The Pendle, as there are some late night descents, but I might just take one on PBP with a couple of extra batteries. I've got a power bank too if I need more charge and as I'm in the 84 hr group on PBP, I'll try and do all my night riding at just before dawn, so I shouldn't need to use it too much. I certainly don't plan on riding through the night at all, but you never know.