Next week I am going to buy a new fish finder. I have an Eagle FishMark 480. I am looking at the Eagle SeaCharter 640 DF. http://www.basspro.com/webapp/wcs/s...1_90974_200001003_200000000_200001000_200-1-3 Does anyone know anything about this one. I would like to hear any pros or cons about it. I would like to get this with a 7" screen. Anyone know if I can find one like that? Any help is appreciated.