How about a lehner

[BP-Revo]

On top of the whole "buy 2 more Mamba's before the cost of a Lehner," Castle will probably warranty your motor and give you a new one if you fry it when its running in a reasonable operating range and its not old enough to suggest wear and tear was the reason it failed. Since Lehner is in Germany, you will be lucky to get the motor back within a few months, if they warranty it.

So, the Mamba's are really the way to go.