Project Estate Agents VS Local Estate Agents

We are looking into selling a multi-unit with basement development in Melbourne (Construction to commence early next year).

Does anyone have any experience with using Project Estate Agents (who specialise in off the plan sales like a Castran Gilbert). Are they worth using instead of a more local Estate Agent like just your local Jellis Craig or Buxtons for example.

I know the Project Estate type want 50% commission upon contract signing but are they worth it? Do they generally sell property faster and for a better price than a Local agent?

Thanks.