The beauty of this isn't terrain on the 400/500W series, but the low cost (relative term) EFIS Garmin is introducing that is helicopter specific. We fly the G600 in a float plane and the displays and synthetic vision are a big help in areas of terrain. Here is a photo from this past summer showing the displays and synthetic vision.
The Sagem integrates engine displays, where the Garmin relies on the factory engine gauges. The Garmin is a fraction of the cost of Sagem or Chelton, and to my eyes, has much, much better displays.
Not sure where you fly, and land whenever you enter yellow on the 430/530 terrain page. Most flights, we disable the terrain alerts on the 430/530 as we generally don't get high enough to get out of the yellow/red area.
PS: At the web link I posted above, I see that Garmin is also introducing an Iridium based flight tracker.