Are the bottom two examples the same display resolution as the images you posted appear to be?
I assume you mean the comparison of the Nuvi 3550 and Montana 600? The Montana screenshot is at its native resolution of 480x272. The Nuvi 3550 has a native resolution of 800x480, so I scaled that to 480x288 to match the height of the Montana image. The screenshot at the top of the page shows the full 800x480 resolution of the Nuvi.
Garmin just released their first outdoor gps with a 5" 800x480 screen last year, the GPSMap 276cx. it has been very controversial and problems with early units really alienated some of their loyal customers, many of which returned them. Hopefully they are addressing these issues, but some people feel the processor is just too slow to provide decent performance. Looks like a nice device, but for $600 I'll pass.

With this map, I have found that it looks ok on almost any Garmin device IF you zoom in far enough. So while that screenshot on the Montana looks terrible at .3 miles, at the 500 ft. zoom it's OK.
But really, these devices like the Nuvi 3xxx are probably just an anomally in Garmin's line. The higher quality rendering doesn't make much difference with the maps that Garmin sells.
