i would have done Switch sub {...}

Ok, but without the sub is also not uncommon, for example I'd say Try::Tiny's sub try (&;@) clearly looks better when written try { ... } catch { ... };.

In regards to your other post:

the whole (logical-test) && do { process-stmts} ; setup while legal is very "un-perlish"

I disagree, I think it's very perlish, in fact probably "too" perlish! ;-)

given/when

Note that these were retroactively marked experimental as of v5.16, and will generate warnings in Perl v5.18 and above:

It is clear that smartmatch is almost certainly either going to change or go away in the future. Relying on its current behavior is not recommended.