I always say that the volume between Forex brokers is relational. What I mean is that if you are using a fairly large broker or ECN broker then typically even though the volume amounts might be different between them the bars are relationally the same.
IE a no demand bar on one broker is typically a no demand on another broker.
The only times I find this might go awry is during what we call Dead Zones (Lower than average volume/activity periods) but I would say you shouldn't trade during these periods anyway.
That said I find Broco (BrocoTrader Platform) to be an excellent source for volume as is FXPro and FXCM etc.
I would also like to mention that we are planning a stand alone version which will allow you to use multiple datafeeds (mt4, esignal etc) This will likely be a free upgrade for anyone using our current mt4 version.
For more information or if you have any questions about SMART Trader Volume Spread Analysis (VSA) Software please visit
SMART Trader at pipbuilders.com or visit our Live and Free VSA (Volume Spread Analysis) Chat and Trading Room at http://vsa.pipbuilders.com
Good luck trading and see you in the chat.