I cannot get the AGS to work for me because of the issue you're describing, and also, not matter where I have the volume on the pedals or bass before it, I hit the AGS way too hard to sound amplike and be reactive to touch. I run active basses before it, which shouldn't matter really, and the compressor output very low. Still doesn't work the way it should at least in my head. The tonehammer basically an EQ machine/DI for me and very little else - sometimes I don't even use it for DI if the house prefers a J48 or JDI or whatever. It will likely get replaced by a darkglass ultra unit or a shiftline - I use every pedal on this board for bass and the least useful of them is the tonehammer right now.
The AGS on the tonehammer, which granted I probably have never heard correctly, but based on the gain on an actual tonehammer head and my experience with the pedal, is warmer overall than the Glacial Zenith, or the Mayflower for that matter.
The Glacial Zenith can go from very clangy with the shape knob dimed to warm to muted when zeroed. Its OD range is huge. There's a bass cut option too, which is great for when this used for guitar. The boost can be before/after drive and can be used independently as well. Every knob on this thing has a lot of range, it's a great pedal and won't be going anywhere anytime soon.