Thoughts on EF 500mm F4 with Mirrorless Body

[batmn319]

I’m thinking about trying to pick up a used EF500mm F4 to use with my mirrorless bodies. 

Obviously there is a huge price difference between I and II, but I thought I’d see if there is any experience with one or both on here. 

I’ve read at least a bit about some AF challenges with the I’s on mirrorless bodies. 

Insight and experience welcomed!

[shadowsports]

This is a female eagle.  RF 100-500, shot from a platform under a canopy in deep shade.  She was hopping around quite a bit and had a fish clenched in one foot.    

 RF 100-500, 500mm, 1/640, f7.1, ISO 160