MBQ wrote:

Assuming the plastic is a better insulator than metal then I would say
they are less likely to freeze up. How much longer they take to freeze
and whether it's a difference worth writing about, I don't know.

Of course there will be a very small difference - the brass tap will
freeze slightly sooner than the plastic tap - but the difference will be
so small as to be totally inconsequential.

--
Grunff