But I went with the single stage, even though with the additional rebates the 2 stage would have been only $150 more. The 2-stage is nice during milder weather for increased efficiency, BUT- Lots more to go wrong. Only 20 warranty on the heat exchanger compared to lifetime on the single stage. MUCH more expensive to repair.
The only thing I'm a little disappointed with so far with mine is the amount of noise the combustion fan makes. Otherwise Im totally satisfied - so far.