I got a quick response from the FX Engines CEO regarding my and Wim's concerns stated in the previous post:

I will answer that with three points:

1 - We do not intend to always deal exclusively with FXCM. We really enjoy our relationship with them but it's not exclusive and it's always been in our plans to add additional dealers.

2 - We have a relationship with them that is very good. They know what we are doing, and they know we are not dealing ahead of their prices in any way. I don't expect them to put our accounts on manual, but if they did we have channels with them to work that out. There will be trades where their whole system goes to manual, and there's nothing we can do about that.

3 - We don't do anything that creates riskless trades (as some traders do who deal in advance). That is usually the only reason a trader would go manual. The difference between us and a trader is we can show demostable evidence that our system trades exactly as it should, as we say, whereas a trader cannot always provide that.

Overall I don't think we have a problem until we have a problem. So far, so good. We just executed literally hundreds of trades in seconds, fully automated. It's a highly functional system.