Mo,
I think I see the source of misunderstanding between us.
He is talking about a tankless system.
Manual Flushometers | Sloan
Therefore his flushing capability is mostly dependent upon the flow rate of his supply. The accumulator should provide an adequate flow for the period of the flush.
Yes, deposits in the waste trap can cause degraded performance as well.
Sorry we've been comparing apples and oranges.
Les