I think that I finally have enough information to make form a educted opinion. After speaking with the various sales people, garmin reps., 240 owners, and other assorted experts; it looks like I purchased a unit capable of reading the bottom and showing large bait balls. But, I shouldn't expect it to show individual fish accurately, or if it does they could be shown as a dot or line or something.
The only problem is that I purchased the Garmin to give me a better picture than my hummingbird(good thing that I did not remove the HB).
The 240 blue seems to be a f/f trying to fill a cost gap between the cheaper units and the more expensive ones. I'f I had it to do again, I bet that for just a few dollars more a 340 by 340 unit would have been the way to go.