Get the new one! I have heard some great things about it. Yes, it is critical to have one on board. Will you catch fish without it? Heck yea! Will you catch more with one? Can't say you will. What i will say though is you will have peace of mind knowing your lure speed, and you will also have some good info as far as temp is concerned. That comes in handy on a slow day. This way you can put your lures in the right area.