If there was a superintelligent EA (I say super because it would have to be more intelligent than each of us, because we ARE intelligent and it hardly means that we mulitply our accounts), then making money on FX would be piece of cake, so if everybody started to make a lot of money the money would become less and less of value. The only option would be to make the EA superexpensive -- so then again we would not have it (so I guess we are bound to get inferior EAs). Who would really sell the hen that lays golden eggs?
(Now if some one says that they created artificial intelligence super etc advisor that will always make you money in a more or less 100 KB snipet of code they simply lure you into parting with your money, full stop.)
Coming back to GT/RM, their concept is quite simple and there are two basic conditions that will need to be fulfilled: a) the price
range 
cannot be exceeded too much b) you need to have some safety allowance in your capital to manage situation when price
range 
is exceeded. That's why the EAs author insisted that we use Balance Factor = 3500$. Anyone, who used this value would have be able to sustain quite a large
range 
breach...