So basically you are saying go with any style and it will still be great since immutability is enforced by default and when using mutability it will also be safe with the ownership rules.
I guess I agree with you.
The key point is as in FP style languages like clojure there is immutability by default.
However, in rust, the immutability is NOT dependent on using functional style.
As a best practice, one should limit mutability and rust conveys that by its ownership rules.
The difference with languages like ruby is that they also allow both styles but then they don't keep mutability safe like rust does.
Sometimes giving options is more of a burden to decide but in this case if we are getting similar safety and performance results, then answer is :
do what you prefer and if you are in a team try to make everyone consistent with a given style.
In my case, I would use mutability only when needed. Use FP style in general.
Thanks for your inputs.I think I got my answer