One project that I helped design had to split out a segment of the system b/c the data was eligibility records coming from health plans. This data had very different security and lifecycle requirements (e.g. we have to keep it for 7 or 10 years). Splitting out this service simplified some parts but any time we need to cross the boundary between the 2 services, the work takes probably twice as long as it would if it were in a single service. I don't think it was the wrong decision, but it the service definitely did not come for free
