People are resources: every users should have a personal calendar - team calendars should be about an aggregated view of personal calendars

I think your implementation of "people" calendars could be improved if:

• consider people as resources with availability. (similar to cars, meeting rooms, laptops...except that those resources blindly accept requests, where people to varying degrees (dependent on how empowered they are in their workplace) manage their own commitments and availability.
• each user has their own personal calendar.
• calendar items sync across multiple calendar views (events, team, personal...)
• a team calendar is not about adding things to the current people calendar...but about a user sharing their personal calendar (controls needed about sharing details of events in personal calendar - i.e. I'll share I have a meeting..but not share a sensitive medical appointment...but availability should still be blocked out.) Users are added to the team calendar and availability/calendar items flow across.
  -events (such as a meeting) allow aggregation of multiple users into one item on a team calendar

Initial key here is that every user gets a personal calendar...adn the people calendars become about adding people...not people adding personal events...they add those in their personal calendar and may choose to sync with iCAL or Exchange.