IMO, $6/mon is more of a nuisance than a hindrance. One has to wonder, though- why six dollars, as opposed to twenty? I would be just as likely to pay $20/mon as I would $6/mon, if I think that what they're offering up is even slightly better than what than Google or Zoho offers.

So, the problem isn't so much the fact that it's not cost-free, but that it's cost-free but cheap. I don't like cheap.