Another update - I finally got the rest of the costume painted, decaled, weathered, and worn! I've held off on photos because I'm waiting for my "pro" photos from the con to come back, but I did take a few hall shots and such for the meantime.
For starters, my helmet got a little extra TLC and a name badge, plus a weathering pass. I opted to go light on the weathering, focusing more on raised edges that would get worn away from things like rolling around in a kit bag and light scrapes rather than serious trauma.
I've made a mental note to either replace or darken the visor somehow down the line; it's far too transparent for my liking right now, but I didn't have time to fix that before the con. That was time that I spent with my girlfriend, who helped me frantically weather the hell out of my armor, washing it, weathering it again, washing it again, and so on until I got an effect I liked. We ended up using two shades of gray as mentioned - one "base" pass with the darker gray, and one "highlight" pass with the brighter gray. The brighter gray was also later used to create sharper scratches where debris may have hit. We also spent a little time putting more wear and abrasion on the left side of the armor set - since I'm right-handed, one can conclude there would be more wear on the side I'm pressing into cover with, rather than having equal wear on the shooting side that would be exposed more frequently.
Here's my torso both before and after the first weathering pass. Note the red "emergency release" tab; I thought it was a super cool detail on the in-game model that a lot of people leave off. It's just the end of the strap woven back and wrapped in colored electrical tape, but it adds some decent character. I then added decals as well; while I think I scaled them too large, they have a much more dramatic impact that I liked in the end anyway.
Complete armor set, laid out and ready to rumble after final weathering:
And finally, the complete costume the night I took it out for my photoshoot. Hopefully I'll have those photos back in a week or two so I can share them as well.
Bonus: