I'm using the Hummer low end, can't spend the $ for the bigger ones although I really like them. I also think they will come down in price just as the flat screen tv's have, labtops, digital cams, ect. I've got two guys whom I fish with and they have the DI/SI models that are really nice. I've just settled for the Nav package on my I phone to navigate by recently but finding that all important brush underneath the surface would be nice.