> PS as a matter of form, is it considered impolite to make
> this sort of small reply to the group, or should I direct
> this sort of response to an individual?
I went to the archives and retrieved the following, which
I sent to the list back in 1999. I think it's still good
> Expressions of thanks are like manna from heaven and mother's
> milk, BUT it is generally best to send them privately to the
> happy recipient rather than to the list at large.
It was very thoughtful of you to ask. That applies to messages
whose main purpose is to convey thanks. It's always acceptable
to tuck a "thank you" into a message that responds with further
information or discussion. Whether "I agree" counts as further
information is matter of interpretation.