+13 pips today and not even on an ECN-broker :-) nothing on the 2nd account.
Regarding business models of brokers see the filing of Gain Capital (forex.com) how they make money (page 90 ff.)https://www.sec.gov/Archives/edgar/data/1444363/000095012309039802/w75376sv1.htm
So for market makers it is imperative to hedge their market exposure, first internally by netting all clients' positions, second by making opposing trades on the real markets for the net exposure. That's what takes them so much time opening a client's order, they simply have to hedge first and that's why some brokers are not suitable for MDP (because it takes them too long to hedge, market has moved in the meantime and brokers rejects clients' order ('requote')).
So you most probably won't succeed with MDP on a market maker-broker.
For MDP STP with DMA (Direct Market Access) would be best, I guess. But still you can't be sure whether the broker sends ALL the orders to the liquidity-provider. Usually they will build account-groups according to lot-size, profitability etc. and treat each group differently. And regarding ECN: most brokers who claim to be ECN are not! They are mostly STP.
In the end, to find a suitable broker for MDP you have to try out each broker and check execution-times, because low execution-times (around 500 ms is fine) make MDP succeed, in my opinion, no matter what methology the broker is using for executing your trades.