New Marz seems great...
Let me apologize up front, I'm not very good at doing comparisons, I guess I'm just not attentive enough to small changes.
So I got the Marz Marathon XC for my HH100x. Its 120mm travel, air/coil. It has adjustable travel, however, you have to release the air from the shock before making the adjustment - so its not really "field" adjustable. It has 5 different settings for various "terrains" which is basically a sensitivity setting. It also has ETA, which is a knob that instantly drops the fork from 5" to 3" of travel, theoretically for going up hills - enacting the ETA makes the travel noticably stiffer.
Removing the crown race from my Fox fork was a bit of a hassle, but ultimately not that big of a deal. I cut the steerer 3/4" longer on the Marz, just to try that out as well.
Out of the box the fork is a bit heavier than the Fox Float, on the bike, I don't really notice it. I really like the handlebars up a bit more with the longer steerer - I'm definitely going to leave it long. Overall I really like this fork, its smoother than the Fox, especially on the small hits/stutters. I really like having 5" of travel, I noticed that mostly when going down steep rollers, I felt less likely to get pitched over the front.
ETA works great for climbing non-technical stuff, stinks on the technical stuff. I did an A/B comparison on a very technical climb yesterday and found it was easier than it used to be with ETA off (which was a bit surprising), almost impossible with ETA turned on. I did like the ETA on the few fire road climbs I did yesterday.
Probably the biggest difference I felt was in the air. I was going higher than I normally do and the front was floating up nicely. I attribute that to the fact that the front is starting higher up. I will have to get used to it or I'm going to end up going over backwards.
I'll know better after a few more rides, but my initial impression is very favorable. I was really concerned being that I was starting with what I have long considered the "best" fork, no cognitive dissonance here.
John