Well this is just opinion and I don't want to start a debate over this issue. I use both chip's and each has it's qualities and downfalls. Depending on the situation and environment contour's can change. The later versions are updated and a little more accurate. Either is not perfect and as you stated are only a guide. I was talking to a Lowrance rep. and he stated chip's now are updated annually but soon units will be able to get real time depth contour like the Navy from satelite. I am certain they will cost an arm and a leg like any new tech. but it is coming.. Until then utilize what you have and learn from your experiences.. ... tight lines.....