P45+ has a bigger sensor and a 1.1 crop factor vs 1.3, longer exposure times, larger sensor sites (meaning you can stop down more without noticing diffraction), and I'd be willing to wager has better working DR too or at least the sensor specs show it. Also I'm still a fan of the kodak sensors over Dalsa, but YMMV.
Probably if you had never seen an H body or an Hy6/AFi or any modern DSLR, you'd think the DF is a "Fine" body but IMHO that's an extremely generous viewpoint. Dim viewfinder, no choice of different finders such as WLF or 45 prism, shutter lag, mirror shake are among its worst flaws, and it offers little of the features that the Hy6 does such as focus bracketing, focus trap, rotating sensor, WLF, prisms, etc. The phase mamiya maybe a 'Fine' camera but that's a long way from 'good', 'great', 'superb', or 'advanced'.