A Beta test is usually a call for this kind of feedback. You should send it to them. Save the HN comment for after the Beta.
On the other hand, it strikes me as quite likely that some of them read HN...
(I say this from experience - I sent him an email saying I thought the end of Half Life 2: Episode 2 was really fantastic stuff, and got a response back from the script writer, who he had forwarded the email to :])