The pricing doesn't make sense to me – 4 person teams are penalized vs. 3 person teams. The jump goes from $0/month to $40/month, so the incremental cost for going from 3 to 4 people is steep (at least compared to all the other incremental moves).
Yeah, I think you should be able to pay for support even with 10-20 users. If I were using this in a business as my primary file sharing system, even with 5 users, I'd be a lot more comfortable paying more to get the "custom" support. Although LDAP/AD integration would be really important for most deployments anyway, so you'd already be in the custom tier.
