I have the mh20 and its pretty awesome.
The GT model is just a bit more throwy, meaning the main hot spot will go farther down range with the XP-L HI so the peak intensity is higher than the mh 20 but with the same output. Otherwise they are exactly the same.
I also have the lumintop sd mini which is very similar to the GT to add another option for you, and maybe cheaper if that matters, but its really sold and I like it too,