The problem I ran into using the stock brushed mount is the cast material likes to strip very easy. I've run the stock brushless motor plate with no issues. There is, however, a bit of flex to it which may result in some stripped spurs if you really push it hard.
I run bb 3500 Traxxas and ridiculous gearing. Just got the 1406 4600 in so I'll be testing things out with the plate flex. The higher kv's normally equate to less torque but in this case, the 4600 being 4 pole will produce way more torque. This is coming directly from a Castle rep.