Yin's research shows that the diseconomies of scale vary by investment style. Some styles have more diseconomies than others. For example, emerging markets, global macro, managed futures, and long/short equites all show diseconomies. Managers will continue to grow until that push their returns down to the style averages. Be with the crowd and then just collect your fees. The diversification of the manager is no help. This provides an incentive to grow one fund until you get the diseconomies and then start another to repeat the process.
The message is the same as with mutual funds. If you want to find the exceptional managers, go small and when the manager grows to a certain size, sell, and repeat the process. This takes work be the number suggest that there is potential reward.