As we've been looking at all these CFB vehicles, I have been judging them based on realistic (suspension of belief) expectations .
The key to these is transportability: meaning, for a quick-reaction organization like the JOE Team, the vehicles have to reflect the ability to be transported by whatever means to where they are needed.
The Brawler has some good ideas, but the fact is it is too big to be transported by air (or even air-dropped for that matter). It's too heavy to be assembled in the field or even close to the front lines (of conflict) without heavy equipment.
I can only see this being transported by possibly rail, and even then being transported by cargo ship (Navy roll-on/roll-out ships too) to the area.
All the major weaponry is front facing (come to think of it, so is Big Brawler too)

, so any good HEAT-Viper would just have to lie low until he gets a side or rear view at it. Heck, the Brawler could even be knocked out by a Flak-Viper.
I'd have to give the Brawler a 'C'.
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