So are you saying that the Mammut is brighter than the myo rxp?
I don't have Myo RXP, so this are only my supposings. I am telling about Myo RXP because I considered that model against X-zoom, so I did some comparisons "on the paper".
Surprisingly (for me) on fresh batteries (included alkalines) X-zoom reaches the distance about 120m easily. I tested it yesterday in the "city night" (so there was no full darkness, but street lamps, lights from cars and buildings), and the spot was pretty visible on the building which is c.a. 120-140m far.
Then compare the table which I presented before, with similar about Petzl:
As you see, the light is regulated quite short time for higher output levels.
In fact, according to the specifications, regulated times above level 4 are pretty shord (4h for level 5 and only 1h for level 7)
After 30 minutes of lighting, X-zoom on the LOW selection should achieve similar distance as Myo RXP on the level 5 (MID)
And the light is lasting about 3 times longer than RXP (300h for the lowest and 120h for the highest setting, comparing to the 97 and 50h for the RXP)
This may make this headlamp very good especially for longer camping - you can take one or two replacement battery packs less :")
Funny thing is that the light on the narrowest setting is square... with very sharp edges.