What are the trade-offs of enabling Person Accounts, and how would you advise a client considering it?

The dominant fact is that enabling Person Accounts is irreversible, so it deserves a proper decision record:

1. What it changes: A Person Account is one record surfaced through both the Account and Contact objects. That affects record types, page layouts, sharing, duplicate rules, roll-ups, and every integration that assumes Accounts and Contacts are separate.
2. When it fits: A genuine B2C model where the customer is an individual with no employing organisation, and where you want the full Account feature set — territories, sharing, roll-ups — on that individual.
3. When I would avoid it: Mixed B2B/B2C models where the added complexity is not repaid, or where a substantial integration estate already assumes the standard model. A Contact-centric model with Contacts to Multiple Accounts often meets the requirement with far less disruption.
4. How I would advise: Prototype it in a sandbox, run the existing integration test suite against it, review the effect on storage and record counts, and get explicit sign-off from integration owners. Then decide — and if the answer is yes, do it early, because retrofitting it later is significantly worse.