2630 to a 4640 would be like for like, and Deere has extra trade in money out for those right now. Trading to a 4240 would be a step down but if you KNOW it will only auto steer its whole life then you're ok. If things like planters, sprayers, NH3, toolbars, advanced guidance, etc ever come into play it falls out of play depending on the situation. (where a 4640 wouldn't) 4640 screens are the same as what you're used to in the combine, just the moveable version