To my understanding, quotes provided by IBFX, Alpari, FXDD, and Oanda are highly filtered quotes in which 1 tick is sent to clients once in every few seconds. Whereas, unfiltered quotes are sent to clients up to several ticks per second. Naturally, unfiltered quotes are extremely fast, while the filtered ones are slow. Many third-party feeds except brokers provides unfiltered quotes. Why brokers provide only filtered quotes? Because they can show off tighter spread (from 5 pips to 3 and now 2) while being able to maintain real 5 pips spread transparently from clients.
We'll absolutely need unfiltered quotes to get the precise volume of ticks.