I just run live. If I want to test something I put down another Mt4 directory on the server and let it run. Haven't looked at MT 5, I'm at the stage where I need to get off Mt and go C++ and API's...MQL and C++ is very similar and it's a bit more professional to pitch up with something that can work with all broker platforms, instead of demanding MT 4 or MT 10 or whatever the latest version will be.
On average I have about 7 to 10 MT4's running at the same time. Have to watch for memory leaks though, every now and then it chews through the memory and you start missing trades when CPU usage clocks in at 100%