There is still a significant difference between the Rheem Mod and the York Mod... Warranty for one... The york has what a 5 year parts warranty and a lifetime HX warranty? The Rheem has a 10 year parts and a lifetime furnace replacment warranty, not just a HX or minimal credit for it when the hx is no longer made. If you plan on living in that house, it really is the last furnace you will have to buy.
no one here can tell noticable differences in 1% and 5%. The rheem works soley on the temerature in the room, not some algorithim. The rheem has 10 years of historical excellence and industry awards behind it, the york is a year old knockoff. The rheem has the same temperature rise at all firing rates, not a few speeds.
The Rheem has direct spark ignition. No matter what new hot surface igniter is released every year, it's still a regular service call.
You'd be hard pressed to justify passing on the rheem to by a york over the small difference in price. Granted the customer is looking at the installed price and those differences could have swung either way.