I have this one.
http://www.gpsdiscount.com/catalog/Lowrance-748.html
It made for waterway navigation, not streets.
So it has all the navigation aids, bouys, etc....
iFinder Atlantis This package is shipped with the iFinder Atlantis, pre-loaded MMC card (featuring U.S. coastal and Great Lakes detail with navigational aids, obstructions and wrecks), white faceplate and the package accessories listed below.
I would say WAAS is a must, since the accuracy is there, why not take advantage of it.
I use it as a backup to my Raymarine color unit.
But to compare I have used it side by side at sea and its very good.
Not a color screen, but its the ocean anyway.
Anyway, just a suggestion and my opinion. Good Luck.