You're running about a 2% failure rate, general average within most manaufacturers and not out of line. Hopefully you can understand that when you state "I have been installing Goodman units since 1987. Mostly heat pumps. Of all of the units I have done (I am still in contact with most customers) I have only had 2 repairs." that statement can be misconstrued per quality of the brand.
Given the information you've given me, I will also assume you are by far not the cheapest quote because if you're doing side work like you've described with your full time job, you don't want call backs being a pain in the butt added you mentioned no relatives which tells me you're smart LOL (in 25 years the only "relative job" I've done was my own parents home, and that was a boiler replacement, which I can live with).
If my assumptions are correct, I know more than a couple of guys like you locally in my area. Thing is, people assume since you're small, you have to be cheaper and you're not

That said, you're not Goodman's typical customer by far.
Out of curiosity, do you push the brand or do you push the quality of your work?