I agree that a BTU rating is what it is. Even if there were some slight difference, the casual owner would not know because he has nothing to measure it with. It gets down to engineering which is beyond the scope of most of us and certainly beyond the casual user.The big difference is the pressures they run at. My R22 units kick off on high head pressure at 425lbs while the R410a units kick out at 575lbs. The suction side runs at almost twice what the R22 units run at and all of that takes some getting used to.
Dometic started building their marine systems with R410a back around 2007, but we are just now starting to see problems with them, probably because of the age of the equipment. That's going to be the norm with any generation of equipment. And that is just a generalization. I have 20-25 year old R22 equipment out there that still have the factory seals on the service ports.
