I have the Wiz20 and am very impressed and pleased with it. It usefully has two modes you can set it in, one with two levels and one with three. You can also set any any light level you want as well in 10% increments up to the max of 1500 lumens.
So you could set the twin level to be say 750 lumens (low) for slower climbs and 1500 lumens (high) for faster descents. With only two 18650 cells in the Wiz20 runtimes will not be as long as a light with a 4-cell battery pack but it would be very easy to carry spare cells and switch them on the trail. The back of the light comes off very easily for changing the cells.
It is a very well built light as well and well above the average quality of most (if not all) Chinese lights I have come across. Right up there with the likes of Gloworm and Fenix I would say.
One thing you do need to be mindful of is that the Ituo lights all come with neutral white tint LEDs which is good for colour rendition of foliage etc. at night but it is better if you have a complementary NW helmet light to go with it. If your Torchy U2 is cool white tint, they don’t tend to play very well together as the different colour shades confuse the eye somewhat.
Best to have two NW or two CW tints working together.