This is embarrassing. Maybe for the foreseeable future all my posts should be moved to the "rank beginner" forum. Or maybe the "bonehead" forum. Regarding the sample Epson Exhibition Matte print above - disregard it.
It finally hit me today. When printing on Exhibition Matte canvas i'd set the media type to WCRW. And (blush, mumble) had also set the printer profile to WCRW. In Lightroom it's easy to do and also easy to save. So I'd made that mistake early and nothing was calling it to my attention.
After talking with Randy Carone yesterday I decided to try tuning a troublesome print (dark blues had been going muddy black) in Photoshop (like I did, pre-Lightroom, thanks for reminding me) and going through the print dialog there, it hit me. Boom, bricks, ton of. I sat there, looking at it, looking at all the canvas hanging around my office for a while. Then, shook my head, downloaded the proper profile, fixed it, and tried the print that had been troubling me again.
Gorgeous, just gorgeous. The dark blue tones are... dark blue. No muddy blacks in sight. It's gonna look great once it's coated.
Sometimes it's our role in life to serve as a bad example for others. Posted in hopes of saving someone some trouble down the line.
PS - haven't had the 4900 long, and no one would call Houston TX low humidity, but zippo problems with clogs so far.