Good news!!!
Garmin have some beta firmware: v2.86... get it here:
http://www8.garmin.com/support/collection....ct=010-00697-01
I've done some before / after screen shots. The new firmware seems to make the maps a *lot* clearer for zooms 300ft+
Here you go (v2.80 on the top row, v2.86 below).
Here's another location: