FWIW, the Carrier/Bryant coils are not aluminum, they just look like they are. They're tin plated copper units. As far as warranty, almost all of the manufacturers are giving a 10-years parts warranty that is transferable to a new owner if necessary. Just register it on line if the dealer is too lazy to do it for you. And I wouldn't lose any sleep over the type of coil provided. Each salesman needs to try and get your business and will therefore use every benefit he knows to get your business.
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!