turbo

prices can vary between markets. see attached link regarding furnace options from another location. Your Trane quote is obviously either overpriced or mispriced.
IMO

Here is a link that might be useful: Furnace quotes

Well you can find the rheem furnace on ebay for around 1,500. However, you seem to have several add ons which they usually jack the price up for. My qoute for the same system was $2,800. The april air filter was $395 and the humidifier was $250 in addition. You are probably paying $295 for that labor warranty. Oh, and that IAQ stat cost as well.

IN addition, do they have any big modifications for the install?

I would suggest looking at your local angie's list, where people share what they pay for hvac installs from companies in your area and rate their experience with the companies. It is worth the price of membership. Also, get at least two other rheem dealers to give you quotes.

I personally am comfortable with around $1,500 labor for a well installed system, but would pay more if their were duct changes or something else.

I had some duct changes (chimney liner, damper), added a bypass hunidifier and got a touchscreen thermostat (who can remember how to program them anyhow). I negotiated it for 1100 less than my original quote. Could have done better if it wasn't year end but oh well. Had to take advantage of the tax break.

Not that it's installed, what's weird is the air feels almost cold coming out, but the house is warm. I guess that is the lower stage of the two stage heat.

This is a little late...but I am in Colorado and looking at the Rheem RGRM system. Your quote is thousands of dollars less than ours. WOuld you mind sharing the contractor ? I can send you my email if you would prefer.

Thanks!