I've thinking of maybe getting a 80% dual stage furnance which would be a bit more efficient than a single stage 80% furnance. But I'm wondering if it's worth it. Would a dual stage 80% furnace be as complicated as a 90%+ furnace? Are the parts just as expensive to replace/repair as a high efficiency furnace? Or in other words should I stay away from dual stage furnaces for the same reason I would stay away from a high efficiency furnace (high repair costs, higher chance of break down).