This is a tough one to answer. Do you absolutely love your camera? If not, that's a lot of cash for a repair on a 7 yr old device.
But you also need consider its price when new, and that it was still selling for approx $5k in 2016. Myself, I might opt for a new device with the understanding that you would need to throw another $1800~$2500 to shoot 4K at the relative same standard you have become accustomed to. A move to mirrorless would also involve a converter (cheap) in the scheme of things in comparison to throwing down for new RF glass.
I wouldn't have any hesitation using EF glass on a mirrorless body. The control ring adapters appear to work perfectly. If you are happy with your camera, (meets your needs) get the repair.
If you are looking to step up, and want to own newer tech that might possibly allow you to take work to a new level, with additional creative options, and the benefits of improved tech, color depth, battery life in packages that are half the weight, then a new camera might be the way to go. You have options. R5, R5c or the C70, but none are inexpensive.
~Rick
Bay Area - CA
~R5 C (1.0.9.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It
