Well, a bit of an update. I ended up ordering my EOtech from IRUNGUNS. Jason has confirmed that I got one of the 3 that were left in stock, so that's progressing well. I ended up going with the XPS3-0 since I couldn't find a 552 (or a 517 or even a 512!) anywhere, and the guy on the EE didn't even bother to get back to me.
Got the rifle itself yesterday, and took her out to the range for a bit of play this afternoon. It definitely runs well, no problems with the MFS MilSpec ammo I was feeding it, and it was shooting ~1.5" groups at 25 yards with the Magpul MBUS I threw on it, standing (in snow!), unsupported, and not trying particularly hard to be super-accurate -- it was more of a "does this thing run well?" kind of test. Yes. Yes it does.

My shooting buddy was super jealous and now wants to get an AR of his own.
The factory trigger on mine isn't actually all that bad. The reset is pretty gritty, but the actual pull to fire is decently crisp. I'll probably leave it as-is for now, but I'll look at one of those Geisselle kits maybe later this year.
My only real gripe with it so far (and it's not much of one) is that the Magpul AFG2 doesn't actually fit onto the quad rail properly without modification. The side rails are slightly too low, and snags on a flared piece of the rail attachment side of the AFG2. Nothing too hard to fix -- just took about 5 minutes of careful work with a rasp to file things down so they fit nice.
And finally -- the obligatory pic of my new baby, sans-optic for now: