Only scratching the surface today, hopefully more next weekend.
The battery cover can be removed without undoing any screws by compressing the plastic just a little while angling it.
I did this while considering a mod where I could siphon off power from the 2 AAs to guarantee 3V power for mics.
I got a little more adventurous... Removing top back cover:
2 screws are near the battery cover hinges and obvious, 2 are hidden are hidden under the soft adhesive feet at the top.
Note the positions of the Mic Sensitivity, DPC, and Auto/Manual switches on the back, they will shift when the back cover is removed.
Remove the screws and the top back cover should slide up and out.
Replacing the cover means putting the 3 switches into place (careful to ensure alignment), and sliding the cover back on and rescrewing things back in.
I removed the switches for Mic Sensitivity and Auto/Manual Rec Level from my back cover (bending the plastic) since I always have those switches taped to prevent accidental toggling at shows anyways.
I can still toggle the switches with a fine tip like a toothpick with the cover reattached, though.
The internal mics are removable from their holders with tweezers (but hard-soldered).
You can also remove the mic grilles with one screw each (near the input jacks).
I'm keeping these as-is for now...
I am considering removing the internal mics to put the necessary capacitors and resistors for mic powering (once I get the tools and parts).
I may also repurpose the remote jack for mics since I never use it.
I should also be able to remove the metallic mounting thread since I never use it, adds weight, and is a fairly dense piece of metal.
I'll look under the PCB next weekend to see what free space I can find...