In terms of the Epson, I have tons of spectral data from numerous models from all over the planet. I can show that the difference between multiple Epson printers printing the same target produce an average dE 2000 on over 1700 patches that is half of 1!
Further, Pixel Genius built profiles for Exhibition fiber for the 2400, 3800, 4800, 7800, 9800, and the 880 series (up to the 11880). We received output from all these printers from numerous test sites all printing a 5000 patch target and again, the dE values for even the consumer printers were well under 1!
This is WHY canned Epson profiles are quite excellent assuming the collected data and profile creation was done to a high standard (good Spectrophotometer, good software). The units are incredibly consistent from device to device. So yes, I have the data.
As far as DSLRs, easy to come up with a dE value but far, far more variables and the need of capturing data with multiple bodies in one location! I could easily capture a target in a copy setup. I’d need multiple camera bodies however shooting the exact scene and have the exact raw processing. Then I’d simply use Photoshop to produce a document where there is 1 pixel for each patch, build a ColorList from that in ColorThink and run the dE numbers. Dollars to donuts you’ll see far, far higher dE values.