I don't have the FA* 28-70mm but I have been using the new DFA 24-70mm for some time. Based on my experience and the reviews that I have seen for the old lens, the new one should be better. I would not say it's an amazing lens, but it gets the job done.
At lower apertures I would say it's no match for something like FA 77mm Limited, but it's decent enough for casual portraits or some other stuff. I did not check the edge-to-edge sharpness but it doesn't concern me because usually when I use those apertures I don't want the whole frame to be in focus. Images below were taken handheld:
When I stop down to f/8-f/13 for landscapes (usually I use f/11) edge-to-edge sharpness is very good (for my taste at least). First image below was handheld, for the rest I was using a tripod. I have tried to include images with tree branches so maybe it's easy for you to check the sharpness.
If other things like autofocus speed, WR, coating/flare resistance are important to you then maybe you should go for the newer lens. But as I said, I didn't use the old lens so take it with a grain of salt.