Even if I don't really know if it's working or not.

Clicking on each individual firmware will detail the firmware update and also provide directions on how to update your product's firmware. It costs me however much less saying that it does not work, excluding warranty cases etc. Canon Homepage Canon Support Canon Support Service & Repair Pro Firmware PRO MODEL FIRMWARE UPDATES Listed below are recent firmware updates that apply to Canon's professional products. Otherwise if they break their cameras in the downgrade process I should offer a free repair and should come up with shipping costs and the wages of the repairman in my service department. If I told people it would work I should as a manufacturer give the warranty to them that it will indeed work. If I had a company and would identify a scenario which 2 people does I would also tell people that it won't work. Testing software upgrades /downgrades just cost lots of money. They even say sometimes it is not recommended to upgrade from version x to version x+2 because they don't test every possibility but only the ones many people would do. If a manufacturer says upgrading your firmware from version x to version x+1 will work that means only they tested the upgrade process and they found it be fine. Consider how many people go the way of downgrading. Why not? It would cost lots of money and the invest would not be on pair with the outcome.

To tell people downgrading will work Canon should run software tests for that scenario which they apparently don't do. It's simple why Canon doesn't support downgrading or why they say it won't work. Wonder why Canon said you couldn't do it? I would not have tried. I just wanted some other feedback about that downgrade.

So for that point, as Austin said, Canon is wrong.

Canon 7d firmware 2.0.5