in reply to To & or not to & ?
This question does not succumb to pedantry as much as it may appear at first glance. It is actually a very good question, and one of the nagging concerns which motivated my Subroutine Bewilderment enumerated here and here.
Although the responses were helpful, there was no systematic response regarding ampersand (&) other than basically, "you dont need to use ampersand"... and for me that's far too generic a response.
FWIW, there's at least 1 benefit for using ampersand: when you want to invoke a typographical convention that clearly distinguishes subroutine calls from barewords. (yes, I know, the parenthesis actually does that for you anyway, but as we know from Subroutine Bewilderment, parenthesis are not an absolute requirement ... at least not for brave souls who want to craft subroutines that work like the built-ins 'map' and 'grep' et al...
So this does not really answer your question, other than to suggest it is not a trifling one.