A lot of the inserts come threaded all the way through making the use of the screw in brass weights an option. This would help for broadheads like the adapters will. Nibs are pricey but the point is long enough to add weight inside. Target shooters used to do that. I saw were one guy added two 55grain bullets and some hot melt to up his point weight.
This adding point weight is really a carbon thing. If we wanted more point weight with our aluminum arrows we just got heavier points.