It's those pesky "e" that make the difference
I've always been a strict constructionist, which pretty much doomed me to a career outside constitutional law.
Converting from a Classic to an Enhanced PanelView is, as Danester pointed out, a fairly simple matter. If it were up to me, I'd try to get the PanelView 1200E replaced with a 1400E, which should fit in the same cutout and will directly import the application file.
What Paul said he's trying to do, however, is convert from an Enhanced PanelView (a 1200e) to a Standard PanelView (1400, not 1400e). Those software packages just aren't compatible, as they have different formats and features.