You definitely want your new VHF unit to have DSC capability and to tie it into the boat's GPS unit.
While Cam and I might not agree politically (even though most of what I say politically speaking is to get a rise out of him)
I think his suggestion of having two VHF units is a pretty good one, if you've got the room for two full installations. The one change I'd make is that I would have a second antenna installed for the second unit, and two switches, so that either unit could be switched to either antenna. I'd mount the second antenna on the cockput pulpit... which trades range for redundancy.