I have an older 770 Dewalt RAS and would not trade it to anyone. I am slowly reverting to hand tool only status, but this is one of the power tools I will have a hard time stepping away from. It's my go to machine 90% of the time. Crosscuts, rips, angles, compound miters, circles...what's not to love?
I can't help you with price or shopping as I used mine for years before it was actually mine. My Uncle had it in his shop but he was scared of it and it went unused. So Whenever I needed to whack off a board from off the sawmill, I would use the saw. Finally he just asked me if I wanted it. Knowing its unused history and beefy construction, I would have paid him more but when he said $100 bucks, I paid him on the spot.
I can't tell you the difference between the 740 and the 770, but from experience I know you cannot go wrong with the 770. Good luck on your quest for one.
I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"