He has given me several options. These are the three that are most appealing to me.

1) Infinity Greenspeed Hybrid Heat System
25VNA 5 ton
Infinity 80 Gas Furnace 110,000 Btu
Performance N Coil Horizontal 5 ton
Infinity Control
Honeywell Filtration MERV 10
AHRI# 4602945 SEER: 17.60 EER: 12.15 HSPF: 11.20

2) Infinity 17 System
24ANB7 Infinity 17 Two-Stage Central Air Conditioner 5 ton
Infinity 80 Gas Furnace 110,000 Btu
Performance N Coil Horizontal 5 ton
Infinity Control
Honeywell Filtration MERV 10
AHRI# 4648327 SEER: 16
EER: 12.80

3) Trane XL20i System
XL20i Air Conditioner 5 ton
XC80 Gas Heating Furnace 110,000 Btu
Trane Comfort Coils 5 ton
ComfortLink II Thermostat
Honeywell Filtration MERV 10
AHRI# 3220771 SEER: 16.75 EER: 11

I know it is not apples to apple since the greenspeed is a dual-fuel system and the others are straight gas furnace. I am leaning towards the second option since it is 4,069 cheaper than the greenspeed. Does anyone have thoughts on this? I have gotten several other quotes, but this company seems much better hands down.

Make certain you have adequate return strategically located for good airflow which will help overall comfort.

It is difficult to believe you require a 5 ton condenser. Hope you have the load calc in writing on the software letterhead. How would you describe the insulation properties of your home?

You would need to list your electric and nat gas rates to determine if dual fuel makes economic sense.

New refrigerant lineset is included?

On the new supply lines, what exactly is proposed? What R rating insulation?

Just on the info provided, I like option #2 best but correct sizing is
important.

IMO

I would honestly like a 4-ton 2-stage cooling unit hearing about your sq. footage. How tall are you ceilings? do you have an shade? is your attic well insulated?

Thank you for your help. I have not seen his heat load. He says it is in between 4 and 5 tons. My rates are 11.2 cents / kwHr and 4.7583 / MCF. There is a new line set and line set cover. The current line set runs in the walls. It would be extra to put the line set in the wall.

Here is the details on the ductwork:
Supply Duct
Install new metal supply plenum on evaporator coil
- Remove all metal ducting in attic.
- Install all new R-8 ducting to each area of the home including:
> Remove and enlarge the supply boot and duct work to the: Office and Workout Room This will include: removing existing supply boots, cutting in larger supply boots and R-8 ducting. These areas require additional supply air.
>Install an additional supply duct to living room and kitchen area. This will include cutting in a new supply boot, R-8 ducting and supply register.
>Enlarge supply ducting to family room and master bedroom. When we install the new R-8 ducting for each area of the home we will be enlarging these areas to im prove air flow.
-Seal all supply boots to sheet rock to prevent air leakage

Return Ducting:
- Install all new R-8 ducting for the return air.
- Install two additional return air opening for this system. This will include framing return
air opening, R-6 ducting and return grilles.

The insulation properties of the house are okay. The windows are original. There is around 7" of fiberglass insulation in the attic.

If I am reading this correctly and your nat gas rate as listed is all inclusive, then it is inexpensive and dual fuel should be tossed in the trash. This rate would be as expected since you live in Texas.

You do need to see the load calc in writing and review carefully.

While relocating the furnace to a central area is a good idea, generally speaking hot cold spots within a home are usually a symptom of a poorly designed/size ductwork system. Now is the time to remedy and this should be reviewed carefully with dealer on what exactly you have now and exactly what he proposes.

I would want all R8 ductwork insulation both supply and return runs and trunk lines.

IMO
Good Luck!

so they are taking out hard pipe & re-installing
flex?

not only should supply boxes be mastic sealed
at sheetrock cuts, but ALL ductwork should
be mastic sealed. plenums to equipment should
be mastic sealed and framing for return airs
should be caulked to attic floor, and all
framing members caulked.

have you looked into open cell foam for the
roofline?
this would keep ducts & equipment in a
semi conditioned attic and greatly
reduce overall heatgain from attic
into living space.

if you put ducts & equipment in vented attic
esp with high efficiency equipment, the ducts
will condensate. if they are laying on insulation
and not strapped then you will have wet insulation
on attic floor.
high efficiency equipment will run in low speed
most of time. this means air is colder exiting the
plenum. this equals more condensation.

check into the option of foam insulation.
in my area we put 6-7" of open cell in
rafter bays. this covers faces of 2x rafters
and completly fills bays.
meets code, unlike 3" 'average' bids.

works well in my climate, which is hot
humid like yours.

best of luck