[OpenAFS] Alternative AFS-Implementations

[FBO]

Hi AFS-Fans,

Does anyone have experience with "alternative AFS-Implementations"
(different from OpenAFS)?
What about ARLA or MS-AFS? What are the differences, advantages,
disadvantages, critical bugs,...
Performance and stability ist most interesting.
What are the best arguments for and ( I hope they don't exist :-) )
against OpenAFS?
Are there any Documents available, comparing different AFS-Implementations?

Thank you for all answers.

FBO