Not to worry. Trane has not started using micro-channel evaporators. As far as their residential units, the only thing that I am aware that they had micro-channel in was the cheap XB300 ac units. York also has used them in their residential ac units. United Technologies, Ingersoll-Rand, JCI, Lennox, Rheem, and Nortek are all using micro-channel in their package units though. Some just the condensor, other the evaporator too. Micro-channel coils in refrigeration systems make for a very low overall charge of refrigerant in the system. You cannot pump the entire system charge into these coils the way you could tube and fine coils. Also, charging is very critical on these systems. Too much refrigerant, high head. Too low, you have flashing of liquid before it hits the metering device. I am not the biggest fan of these coils either. Nortek as far as I know is the only manufacturer with micro-channel split system evaps and heat pumps with this coil with their unique defrost system.
Now, as far as all aluminum tube and fin evaporator coils go, this change is long overdue. Like you said Washman, copper is great to braze leaks on. Only thing is, nowadays due to the DOE and ever increasing efficiencies, manufacturers are internally rifling the tubing and making the copper tubing paper thin. Combine this with the fact that a lot of the copper is recycled and processed in China, and houses are being built ever tighter with fewer natural fresh air exchanges, also when dealers oversize cooling equipment to the load and have short runtimes and very little condensate "rinsing" the evap coil off, you have a recipe for formicary corrosion.
Many older dehumidifiers used to have a coil of aluminum tubing for the evaporator with no fins, and then a standard copper tube aluminum fin, or painted steel wire fin condensor. These units generally were a lot less prone to refrigerant leakage but less efficient due to the evaporator not having more surface area without fins. This is a big reason why a lot of modern dehumidifiers don't last as long. Also, many refrigerators both new and old have an all aluminum evaporator to better cope with some of the gasses that condense on the evaorator that turn into a mild acidic condensate.
I agree that if things were made the way they used to be, we would not have this problem. But for now, all aluminum evaps are the best solutuion. GE central units, like Gusherb94 said, became Trane's residential division around 1982. Ge had been using all aluminum spine fin since the 1960s. They also started making all aluminum tube and fin evaporator coils in the 1970s, Carrier and Bryant used all aluminum coils in some of their outdoor equipment in the 70s if not before then. Carrier had their E-coil and Bryant had the green painted aluminum tube and fin coils. Both Carrier and BDP had all aluminum evaporators like Trane did too in the 1980s. Both Trane and Carrier BDP switched to copper tube evaps in the early 90s as making the aluminum ones was actually more expensive than copper ones. But, by the early to mostly mid 2000s, United Technologies, Trane, and Goodman were starting to experience higher failure rates on evap coils. Trane was the first to come back with all aluminum coils in about 2007-2008. Goodman (now owned by Daikin) made their first all aluminum shortly after. Now, the only manufacturers not using all aluminum evaporator coils is Lennox and I believe JCI for the most part does not either.
Sorry for the very long post. I do not mean to flame you Washman as I have a lot of respect for you and Combo52. Shucks, I own two AWN542, one still new in box, and an AFN51F because both you and John.
Thanks and take care. BTW, congrats on your nice new home. Looks great!