I heard great commentary on a podcast suggesting the use of an App instead of implementing business unit security. I can definitely see this as an option in some cases. The App could limit the views that someone has and in essence the records they have access to via those views. Sure is simpler than adding the overhead of business units if it is not truly required.
Was thinking about this after listening to The CRM MVP Podcast, episode 53: Top 10 FUNCTIONAL TRICKS in Dynamics 365.