The ampersand is ambiguous and can be interpreted by perl as bitwise AND in certain contexts. Since it is not necessary, it is better to always omit the &.

Sounds profound, and it got you quite some XP. It should have been negative XP, because your conclusion is 100% wrong. If you you are afraid to get be bitten by the ambiguity you mention, you should avoid using bitwise and, not the sub-sigil. Because whenever perl has the option to parse an ampersand as a sub-sigil or as a bitwise and, it will parse it as the sub-sigil.

    $ perl -MO=Deparse,-p -e 'sub foo {} sub bar {} bar & foo()'
    sub foo {
    
    }
    sub bar {
    
    }
    bar(&foo());
    -e syntax OK
[download]

Someone using sub-sigils in the above case would have gotten the binary and parsing:

    perl -MO=Deparse,-p -e 'sub foo {} sub bar {} &bar & &foo()'
    sub foo {
    
    }
    sub bar {
    
    }
    (&bar & &foo());
[download]

So, you have two options to avoid this ambiguity: either avoid using binary and, or to always use the sub-sigil.