You should definitely be pricing with just heat pump. I live in NC which probably is a bit colder in the winter. We get down to the teens but only 15 nights a year maybe. Our winter average low is about 30. Under 10 degrees is definitely a news story. I have 5000 sq ft. I'm looking at my NG bill of $30. I have dual fuel and seer 16 heat pumps. Last winter was very cold and I spent about $700 with $200 being gas. This winter is going to be $120 in gas. My electric rates are similar to yours without the first 1000 discount. What is my point? Your gas usage will likely be $100 a year. Even if that were replaced with all heating strips, you'd be saving $200 a year or so. Since it would probable be 80% heat pump still, the dual fuel is only saving you $40 a year. So a $2500 furnace to save $40 a year seems a little crazy (on dollars alone). Turns out for me, it is probably worth it but only marginally so. I have a 90% (which you should be able to do as mine is basement with horizontal PVC exhaust). It probably saves $60-$70 on an average year. Probably cost $2000 (new house - I can't remember). What is that a 30 year payback (or never if you count interest or NG rates increase)? You do get some flexibility and you can setback at will with dual fuel. That is worth something.

It is true that the builder's grade (low end) model of the Carrier/Bryant line up is the same as one of the Payne models. The warranty period on the low end and Payne models are shorter for the heat exchanger and parts. Unless you are very tight on funds, or plan to move soon, I would avoid Payne and any builder's model furnace. Spend a little more money and get a better furnace. I am also not a fan of moving a furnace from a conditioned space (laundry room), to an unconditioned space (attic). The move is expensive and the energy performance will be reduced.

We also have a dual fuel HP in ATL (13 SEER + 80% NG furnace). If you're going to invest that kind of $$ in a new system, plus pay to operate it for the foreseeable future, I'd do everything I can to ensure I got a quality install. Below is a link to a Southface Energy Institute fact sheet on blower door and duct blaster tests. They're an ATL non-profit. I highly recommend the info they have on their site. They might even be able to help or point you in the direction of a contractor to design your system and/or test your house/ducts. Ideally, you'd have the blower door done to feed into the Manual J sizing of the system. Then, after your new ducts were installed and sealed (but before insulating), you'd have the latter done to test how tight the duct system is. A brand new system, installed right, ought to leak at about 0.05cfm/sq ft of living space. That's only 125 cfm for your house. If at all possible, you want to maximize the amount of rigid ductwork, only allowing flex duct at the runouts (I'd get at least the Vision Pro w/ an outdoor sensor to control the switch to Aux heat. My understanding is that the IAQ version will handle the staging possibilities better than the 8000 series VP. It also costs more. I'd also be interested in getting a HP w/ good low temperature performance. Our gas bills have gotten smaller since getting the VP set up to control the switch. But on an old house, you're still going to use gas for the days in the teens/twenties like we've seen this winter. Anyway, food for thought. We have used ACS to do work on our system. They sell Carrier equipment. Here is a link that might be useful: Southface on blower doors and duct blaster testing

If the house never had AC, then a load calculation should be done. I think you have mild summers, so 2 ton may be the right size, but it should be confirmed. I am glad the hear the installer took the time to inspect the duct work. That is a good sign. The AC condenser by itself has no SEER rating. The SEER rating is based on the completed system of furnace, coil, and condenser. Change one, and you will get a different SEER rating. You can find the SEER and EER rating on the AHRI directory for approved matches. If you mismatch components, then you don't know what the actual rating will be. You have a single stage furnace. Higher SEER ratings require a variable speed furnace. Attaching a high end condenser designed for a variable speed furnace is somewhat wasteful. It cannot reach it full SEER potential. I can't find the Bryant 310AAV/JAV furnace on the AHRI directory, so I can't verify a match. Maybe I am doing something wrong and someone else can try. I think what makes most sense is the Bryant Legacy 113ANA 2 ton condenser. It should provide a SEER rating of 14-15. I would avoid the Payne since it more of a low end unit. The Carrier Comfort is equivalent to the the Bryant Legacy. Carrier Performance are nice and more money, but won't know what the SEER rating will be.