I do residential replacements all the time, but I operate differently than most comapnies. The thing you should know is that most of the equipment out there today is all relatively the same--I mean they all use the same basic technology, hot surface ignition, four pass chambers, flame rectification, roll out switches, limit switches, and 3-4 speed blower motors. The thing I have found is that even the most expensive piece of equipment with the best known name brand, will fail early if not properly installed. On the other hand I see the least known equipment out there lasting just as long as the best known brand. Just make sure you get about 10-20 references from your contractor then call his refereneces and as them how they found out about the contractor, ask the reference if they know anyone else that has dealt with your contractor--but just know that you will only get references from people that were satisfied. As the contractor for a few references from people who have had a problem with the company, and find out how the company dealt with the problem and if the comapny has ever made it right. If the company gives you a long list of unhappy customers that he has made right ask yourself if you're willing to be on that list. On the other hand if the company says they have no complaints that they have dealt with, then two things can be, one is the company is not telling the truth or that there is only one person in the company and the other is that they have outstanding service. Another thing you can do is go to the city building depoartment and ask for a print out of all of last months permits, its public information, then look to see how many jobs the contractor has done in your city, then you can call the home owners or ask the contracotrs about the jobs and ask if you can have those phone numbers as a reference, if he says no then you know there is a problem.