For what it's worth - I can fully quiet a repeater roughly 18 miles from
my home, having radiant heat barrier, with my 2 M HT at 5 watts but not
2 W - a local repeater around 7 miles away with 1.5 W but not 1/2 watt.
Kenwood TH-K2AT with Diamond SRH77CA antenna (18") in place of the
rubber ducky. Oh yes, those are with the aluminum storm panels in place
on the windows too.

I guess it won't hurt us to try it with HF will it?

Thanks for asking the question, I've been meaning to.