We deal with metamerism fairly frequently. The problem is every showhall in the country has different temperature ambient light. We have to seam 100-200' long covers together to create one cohesive image. The roll to roll differences are no joke. I'm limited to the size of stock I can get my hands on for some projects. We also run into alignment issues if anything gets printed out of order. Our finishing process involves tension heat and pressure. We haven't had much luck seaming together different rolls of stock. Sheen angles and differences become a problem too. Printing large stuff like this can be a one off type process. The problem with proofing is I can't reproduce all of the variables on a 24"x24" proof that I will encounter in printing a 50' long wall. Things like inkload, humidity and fabric batches are all factors. We also have the obstacle of how easily the fabric lets the gas pass through. My magenta burns off first, so some of the less breathable woven fabrics come out warmer in color temperature.
The biggest thing I learned getting in to this method of print is how impactful a little process control can be. Not only in your digital workflow but in environmental conditions. I have to shrink wrap my stock within 10 minutes or the transfer
paper does what it is designed to do, soak up moisture like a sponge. There is just so much surface area exposed at one time!
If this happens we have feed problems and get color reticulation in heavy builds. (it looks like mottling)
I print in Seattle, so fighting the humidity is tough.
I see issues on this forum quite often where the problem is more one of these issues than icc profiles, rip formats/settings or printer maintenance stuff.
I do all of the tech work on my equipment so it sure makes trouble shooting easier!