I'm replacing a 20+ yr old gas furnace in a 100 yr old "leaky" house in Portland, Oregon where the avg winter low temps are in the mid 30's, a week or two in the 20's. We also have 2-3 weeks of 90+ degree heat in the summer where cool air would be nice (we currently have no central AC). I'm having trouble getting a firm rationale for going with a nice high efficiency gas furnace with central AC unit vs high eff heat pump with gas furnace back up.
I've had a couple of estimates from Carrier dealers, one Trane and one Lennox. The Trane dealer is the only one who thought the heat pump would be a good idea in our area (he loves his heat pump). I haven't heard too many arguments from the other guys about why the heat pump wouldn't be good here other than the gas furnace as your work horse will last 20+ years, whereas heat pumps last about 12 yrs on average (from the lennox guy). I have heard also heat pumps are more complicated to install so things can go wrong if not done well, the air feels cooler (which may generate more service calls or complaints), utility bill will go up a lot (but utilities are cheap here and have been stable over my 4 yrs here, gas has gone up twice).
Any strong opinions about life span of new high eff gas furnace vs heat pumps?
Any clear concensus on which brand (Carrier, Trane, Lennox) makes the most reliable gas furnace or heat pump?
Lets assume each dealer is equally reputable with installation and service. I'm also not that concerned with the economic pay-off as I am with reliability and performance.