Had two separate techs confirm a cracked heat exchanger in one of my systems. Contemplating replacing entire system (21 yr old 3.5 ton a/c, gas furnace combo instead of just the furnace. I'm in the Dallas area and I'm wondering if a heat pump would be preferable for efficiency and reliability. Do they typically cost more than split systems? If so, are they worth it. I realize gas selling at $13/MMBTU is going to exponentially drive up the cost of firing gas furnaces. And I know that my electricity is derived from gas fired turbines, thus KW cost are going up as well. And I believe these energy prices will be the norm in years to come. I'm not brand loyal but I did replace a system last May with a Trane XL19i. Many issues surrounding the installing company's competence has led me to not use them again. I'm willing to put in another Trane by a different dealer. Thanks to this website and my own bad experiences with a local company I would almost be willing to put in any brand by a good company than some high end system by a bad one. Quite frankly I don't know who to trust in my area. But I would like some opinions on heat pumps and reliability on high end systems (i.e. two-stage furnaces and compressors, dual compressor condensers) versus single stage systems. Is simplicity the best value in the long run?