I think you'll find that you need it for airways from end March next year. We had ours fitted (Garmin) a couple of weeks ago and it has a very pretty display which puts the rest of the panel to shame, I too understand that large parts of the ATC environment can't yet pick up a/c identification but I guess it's progress?????
Wait until we all have Mode S and en route charges (IFR or VFR), that's a real gotcha!