Yes, it makes a difference to some people whether a group is
public or closed. For me, it does. I'm careful what I write in a
public group yet I'm more likely to post to a public group
because I enjoy the exposure. Sometimes when you belong to a
closed group you feel obliged to stay even if you want to leave.
It has a "you're a member now" quality to it, which makes me
feel beholden to it... and I tend to get addicted to the
interesting company.
Yet, I'm weird like that. I'd suggest the majority of people
probably _don't_ pay as much attention to closed/open status
once they are posting.
But... some people may find a closed group intimidating because
it implies a commitment. One is ashamed to leave a group one is
invited to and accepts, so some people will not join in the
first place to avoid that feeling of obligation.
Think of it from these terms: What do YOU prefer to use?
If it makes no difference to you whether a group of public or
closed when you join it, then treat your group the same way:
Make two groups so that you maximize the net you are casting
upon the waters and you will thereby catch the largest potential
pool of people, many of which will join BOTH groups to benefit
from the distinctions of both.
But if you find yourself personally drawn to one over the other,
then go with the type of group that you as a person prefer to
join.
