I switched from the D750 to the X-T1 a little over a year ago and don't feel that I've given up anything in terms of image quality. I just had a 20x30 print made from the X-T1 and it looks incredible even close up (and the X-T1 has a 16MP sensor). The dynamic range holds it own compared to the D750 and ISO performance is darn good compared to the D750. I wouldn't worry at all about image quality between the X-T2 and the D750. If anything, you'll see a negligible difference in extreme situations. If you liked the X-T2 more, but was concerned about giving up the "full frame," I wouldn't be at all. I certainly am not. I made a YouTube video showing my 20x30 print from the 16MP X-T1.
