This is mildly interesting... a comparison of A7rII and A7 prints at 24 and 36"...
http://admiringlight.com/blog/sony-a7r-ii-vs-a7-ii-print-test/
He sez...
"In both sets of prints, upon close examination, the resolution of the A7R II was clearly visible. Everything seemed a bit sharper, with simply finer detail. However, with the 24″ print samples, the prints became indistinguishable to my eye when the viewing distance extended to around 18″. That’s it. Just 18″ away, and the extra detail in the print became essentially invisible. Since a 24″ print would need you to back up further than 18″ to see the whole print, at normal viewing distances the prints are indistinguishable...
The same is true for the 36″ print samples. Both prints looked fine, but the A7R II print was just a bit sharper and more detailed when viewed close up. The difference is there, but it’s not enormous, to be honest. The distance for these to equalize was a bit further, but they became essentially indistinguishable just beyond arms length, or around 30″ away. This, again, is around the normal viewing distance for a 36″ print if you’re fairly close...
The A7R II is shaping up to be a fantastic camera, but the extra resolution may or may not be of use to you for printing, unless you print very large or really like to get up close to large prints. Where the A7R II’s extra resolution really may come in handy is when cropping. A significant crop will still yield images with greater than 24 MP, and an APS-C crop will yield 18 MP images. This means that even heavily cropped images can be printed quite large and retain a very good look to the image, where the same crop on an A7 II may limit you to, say, a 12×18″ print before the print doesn’t look quite as good. In any case, I think that most shooters, especially those who don’t print larger than around 24 inches wide, should feel good knowing that in most circumstances, the difference in final output is fairly minimal at low ISO. For high ISO, well, that will take more investigation and more time with the camera. Look forward to my full A7R II review later this month."
I've pretty much given up printing. One thing which puts me off is that my Epson R2880 seems to need at least one new ink cartridge every time I go to use it. I dread to think what an A3 print out of it costs.