So I'm seeking the opinions from the Perl experts here.

One perl expert I greatly admire is Tom Christiansen. Read his treatise on the subject: Far More Than Everything You've Ever Wanted to Know about Prototypes in Perl.

"Perl's existing ``prototypes'' (...) are really mostly just parameter context templates for implicit coercions"

The only prototype I use now and then is the function prototype "&" - see Re: Perl module for RELAX NG? for an example.