The user-centric vs -rata debate is loud and badly explained. Most coverage argues about fairness; almost none of it shows the arithmetic. For an adviser, the arithmetic is the whole point, it decides which of your clients gains and which loses if the model ever switches.
The pool model itself is settled ground: there is no fixed "per-stream rate". This argument is one level deeper. It is not about what the pool is. It is about who gets which slice of it.
Under pro-rata, every stream on the platform competes for the same pool. A superstar dropping a new album compresses everyone else's share, including a niche client's, even if that client's own listeners did not change their habits at all.
Under user-centric, each subscriber's monthly fee (say £10.99) follows only the artists that listener actually streamed that month. A fan who listened to nothing but one artist all month sends 100 % of their fee toward that artist's slice.
Same total pool. Different redistribution. And whether the switch helps a given client or hurts them depends on one thing: how concentrated their fanbase is.