Chuck-
Don't mean to nitpick, but ya kinda gotta compare apples to apples here. The H87C is a sounder/GPS unit and can be had for about $650 ('net prices). The R435i is GPS only and priced at about $800. Does Raymarine even make a compact combo unit?
Also, a bigger screen isn't always a better screen. Even with its "small" screen, the 320 X 320 pixel resolution on the G178C offers 33% better resolution than the 320 X 240 on the R435i (or the H87C, or H97 for that matter). Better resolution means being able to see more detail.
By the way, it was the Humminbird 97 that I was looking at last year. (At the time it was about the same price as the G178C that I ended up buying.) It has a larger screen 5.6" vs 4.5" but lower resolution. After using the Garmin for a season, I'm glad I went with the higher resolution.