The pricing comes across as something like "forced obsolescence." Forced handicapping? You might not have meant it that way but many of the features in the professional plan are useful for companies of any size. Like Google apps integration is a standard feature. I could see on-prem SSO (I think Oracle does things like this?) but my company deosn't get automatic calendar invites??

In agreement w/ the comment you're replying to, I wouldn't try this because the base features aren't useful enough and the pricing feels very customer-unfriendly.