I have the 176C and I absolutely love it.
personally, I disagree with seb about the unit being hard to see in certain lighting conditions. Maybe I just haven't had the right conditions at the right time of day but I know I have over 50 running hours on it and around 1k miles on the water and not a complaint yet. Yes, the color is WAY cool...
At night, it is the only way to go when you can see red and green channel markers on the unit along with the different shades of depths - indentical to a top spot map... Way cool and a must as far as I am concerned now that I own one..
Get a bluechart CD or the preloaded chips - they are a must to really utilize the capabilities.
I got my 176C off of E-Bay for $400 shipped with mounting bracket, manual and power cords and it had obviously never been used. It may be a refurb even though they said it wasn't, but I don't care - it works great and is under warranty.. FYI - That's cheaper than a 176 on average.. Keep your eyes open and you can get some really good deals.