Have to agree with the 90%. If you go with that you make it more saleable being its as efficant as you can get other then with VS. If its been a peron with an 80% furnace they may realize its really bottom of the line anymore. just look at it if you stay their any amount of time you wont even be paying $350 more being you will be saving that . What if you end up being there 10 years.... then was that a very smart choice?