I would like to share my opinion about powerTradeCopier with stp addon. This solution allows to send order to master MT4 server and to slave MT4 server in the same time. Trade Copier with stp add-on catches order before MT4 master server accepted it. This video will help you to understand how it works.
I tested PowerTradeCopier with stp addon on several brokerage companies and the result exceeded all expectations. Copying latence is zero and in some cases it was negative. I mean, order was executed on slave account first,then on master account. If you do not belive me, you can test powertradecopier with stp by yourself. Especially that you can request free trial version