Yeah people claim 9.00 is great but I'm still on 5.05 and have never failed to load exploit first time, seen kernel panics or anything.
It works quick and easy. I've never had any issues so why change?
If you were above 5.05 already then yeah it's recommended to update to 9.00, but most sensible people still think 5.05 is the best.
Anything in between kinda sucks from what I've seen... people posting "hey I get error blah blah I'm on 6.xx"
There is at least one game that can't get 5.05 BP but I can't recall which, I do know I have it on XB1 anyway so I don't care. Maybe there are some others but they would be a similar story; nothing significant.