I know this because I was testing both at the same time!
To the best of my knowledge, all these systems are based on MACD. To a newbie they look great, but as with all these things, it's a trend following system that gets "killed in the chop", as our American cousins would say.
That is, when markets are range bound, you will lose.
I was completely unimpressed with Forex Ambush MKI. It sent email signals that (riskily) traded an ASC/LabTrend dot before the close of the bar. These signals should only be traded when the bar closes.
As their marketing still insists that their signals are 100% accurate, but they now have an MT4 robot to trade for you in MKII, I don't know how good their signals currently are.
What I do know is, they lied about their performance the first time and I will not be trusting them again!
If you have any experience of this, or know any better, please let me know. I am highly sceptical of anyone or anything that can claim 100% accuracy and am 101% convinced that this is untrue.