If it's not a fact and you insist on it, it's emotional. Do you have any proof of this? There are plenty of batteries out there that work on more than one model of Canon dslrs, and everyone who uses them is happy with them. Some people have different firmware versions. Between two different bodies there are many different firmware combinations. If everyone is happy with the 3rd party battery I see no evidence of what you said is happening. I have OEM and 3rd party batteries too, no difference, both work for me. Of course I keep my firmwares at certain versions for certain reasons but I'm sure you'd get the same answer from people who upgrade their firmwares indefinitely.
