If im honest, I seriously considered the Sony A7 Mk3. As the price is dropping with the release of the Mk4 it did look like a good option but I kept reading things about slight compatibility issues with the canon lenses and certain adapters and like you, can't bring myself to sell all my gear. I've got some pretty nice glass that I wouldn't want to get rid of and have to pay extra to replace with stuff that is likely not as good. You cant argue that canon makes some of the best glass out there, thats for sure.