Advantages You get the best of both worlds. External groups interact with a small group of experts. Specialists focus on what they are good at. Individual use cases are implemented consistently. You get the worst of both worlds.
Generalists are still hard to obtain.
Specialists still may not appreciate and work well with other specialists, although this should be tempered by the generalists. Project management is still difficult. Success factors Good team communication is required. Common architecture needs to be developed. Common processes, standards, and guidelines must be well defined.