Yes the new cab is much nicer, with the larger doors and the hard rear panel. If I am buying a hard cab, I want it to be hard on all four sides not just three.
I think it will fit just fine. The lower part of the ROPS is the same part number. The upper part of the ROPS is different, it tilts forward on the 70 series.
I think if you install the new cab on a 60 series all that would be askew is the ROPS wouldn't nest into those two brackets on the cab, it will be laying back. And I think that can be fixed either by buying a 70 series upper ROPS or just making some extension brackets for those U brackets on the cab so they reach the ROPS.