Call Epson support and see if they can give you a complete trouble-shooting algorithm.
The following works for me (I don't think it will work for you, but it may give some leads to explore):
- I keep the menu bar on my laptop
- I put Aperture on my wide-gamut monitor (NEC PA271W)
- I keep secondary display set to "Desktop"
- I never run full-screen
- I confirm the monitor profile at least once a day, and every time I change monitors (I work in two locations, ea. with an external monitor). By "confirm" I mean that I re-assign the profile, not that I re-calibrate the display.
- I have the external monitor connected directly with an mfr-supplied mini-DisplayPort (iirc) to DisplayPort (iirc) cable. This was important.
- I had to take some care with the Epson set-up. All I can suggest here is most recent drivers. I first got the USB connection to finally work, and then got the Ethernet connection to work properly as well.
I mention all of that because in the thread you linked there are comments about both the external monitor not using the correct profile, as well as the printer not using the correct profile.
I would first confirm (you likely already have) that the printer works properly printing from Aperture with no external monitor. After that, things get tricky.
What I picked up from some poking around and talking with knowledgeable people is that OS X does not do a good job with color. (I was surprised.)
Sorry I don't have any real help to provide. Good luck.