i took my mastodon off - i can't go dh fast (for me) now - and it is a bit more of a challenge in the chunk (which i think i like),
but the removal of the 4+lb anchor up front made a huge difference in getting the bike up/over,
and increased predictability.
To Be fair, the ICT is an anchor with or without the mastodon so the added weight isn't as big of a deal for me....and I run the heavier comp version. I might feel differently on a lighter fatbike.
And honestly, I think riding style plays into it as well. I know my fat bike is the wrong tool for the job in many or most of the riding situations I tend to use it for, but the fun factor is just so high on it. And for me it just got way higher when I added the fork. It just settled the front end at speed.
One thing I may be glassing over is the fact that I also slackened the head angle a bit by adding the fork which might be part of what I like. I run the "STD" Mastodon at 120mm which slackens it a bit, and then I have to use a lower adapter cup that slackens things even further. Back when I did this I even reached out to Surly to see what they thought and they were like "yeah go for it". So it's possible a piece of what I like is really the slacker front end geo.
Slow crawling I don't notice much of a difference. I mean, I imagine rigid would probably be more precise, but I feel like I can still monster truck things really well on this bike with the suspension fork. Swapping between this and my other bikes, I don't notice the heavier front end, but all my bikes have front suspension.
The weird thing is, despite being prohibitively heavy I love little jumps on this thing and I much prefer front suspension if I am jumping. And despite it's weight, the ICT just wants to "pop" off of everything on the trail., but that was the case when it was rigid as well.
I think I just still love riding a fatbike is what it boils down to.