Decision Time?

My Sigma 50-500 has died and can't be repaired but Sigma have offered a discount on a 150-600. This puts me in a quandry as I have been considering moving over to a M43 system  to help my knees. I've been having issues since September and it is a situation that will likely get worse over time.

I'm going to do some print testing from my GX7 to see how that goes.