It does seem strange that Epson US couldn't find you an acceptable LS10000 whereas here in the UK the vast majority seem pretty good and Mike has said they have had a pretty good track record overall, so that doesn't seem to be "this is just how they are" and I can't believe over here we are lucky to have mostly golden samples. The PMs I had a while back form other LS owners suggested there are good units there too. I wonder if you were just being given lip service and they weren't really trying as hard as they told you - I've seen similar things said to JVC owners here when they get units with bright corners, then returned and get a unit with a noisy eshift and are told "this is just how they are" to fob them off. Being told an unacceptable unit is 'within spec' is another common line fed to unhappy customers so they don't have to deal with them.
When I got my LS my room wasn't quite ready for it so I asked my dealer if he could run it up and check it for me which he did. My previous dealer would do the same for most of his customers too and he did that for me every time so I would be collecting a good unit. I think a good dealer is worth his weight in gold and worth the extra bucks than getting one from a box shifter sight unseen. My current dealer also offers free calibration (which is handy as he has better kit than me) either at the lens or on site (him or a local well known calibrator if it's in a different part of the country), so I've been kinda spoiled with the two dealers I've had over the past 18+ years.
You could well be right about there being just a 4K LCD coming from Epson as there was a large venue model shown on an Australian website IIRC, but it would be great if they were trying to get the 4K R-LCD tech up to speed as well. However, if JVCs new 4K units have resolved the image noise problem (bright corners will still be a potential issue apparently), and they add a laser in the next two years, it's going to make things even harder for Epson or Sony to to sell their products. Right now JVC are making Sony's 4K offerings seem pretty poor and overpriced in comparison, and that's with a preproduction unit that doesn't even have a working iris.
I'm hoping to get to see one later this year and in split screen with a 4K Sony (probably a laser 760) and the LS10500 if he still has it, so that will be an interesting day.
Oh, and are you guys having any problems getting onto avs the past couple of days? I get the top part of the page but not the content, so have to refresh a few times to bring it up. This is the only site I visit that has the problem so I was wondering if it was the site or something else. I cleared my cache and that doesn't seem to have helped much.