Excuse? Not really. Combine the fact that the entire US is loaded in and I basically can store unlimited maps, routes and waypoints, plus my tunes and other stuff for 20 bucks, the Zumo pretty much rolls right over the 276C. Plus your 128 meg route is pretty limited to a narrow, little corridor that would exclude areas that I might otherwise wanna go check out if I wished to deviate from the route while on the fly. I will give you that the screen clarity is indeed superior on the 276.
276 and Zumo are very diffrerent classes of navigator - though today you would more likely compare the 478 with trhe Zumo I guess. - note the differences . . . 276 has the extra I/O and Marine modes. 276 has the higher resolution display. 276 has the 16 hour batery life. Zumo does music and connects to your phone if we're discussing the 550 (the 450 doesn't have Bluetooth). But I have a luetooth interface on my Autocom and my iPod plugs into my Autocom and so does my passenger.
I prefer to carry my iPod over having to synchroniise several MP3 devices, so I don't need or want my navigator to be my multimedia center. I also don't like the new dumbed-down displays that Garmin ported to the 'consumer' models.
I want my navigator to navigate. Masters specialise. Generalists seldom excel at any one thing.
And you get no more routes or waypoints with more memory - just more map.
My reference to routing to LA from NYC was simply to illustrate that you really don't need all THAT much memory to get reasonable coverage..
Unless you are a long range tourer there is not much you can do to outride what a 512 meg card stores. You HAD the 276 - $120 or so would have got you the 512 and you'd have kept the awesome screen and longer battery life of the 276.
Then again, I like the tracklog (I've gotten out of several tickets because of it, among other things) and I like to record my travels so I'd need to bring along a laptop on a long trip to extract the track anyway - so loading new map chunks wouldn't be a hardship if I was to take another 'round the continent tour'.