Not sure I totally understand which service you are referring to, I assume you are talking about the pre-planning service (Disney Signature Services, DSS) available to Club Level guests? DSS's services are also available for your stay if you book a private VIP tour, if that's what you mean?
If so, then no, no advantage in getting DSS to book your FPs, in my humble opinion. DSS sees the same FPs you do. Also, their office doesn't open until 9AM ET, whereas FP+ booking begins 7AM ET - so that delay 'can' be a potential negative for select hard to get FPs if you're really picky with your planning. They certainly are available if you'd like to use them, but no real advantage in my view.
Sorry if that's not what you were asking about.