From what I can see, it appears that the OP's bracket (post #22) attaches only at the 2 long bolts thru the water pump. I don't see a 3rd bolt to the head, like the factory brackets and all others shown here. I would expect the alternator mount to be springy in the sideways direction. At a certain rpm, it might start oscillating and perhaps eventually break the bolts from fatigue.
the KRC mount uses the same attachment points,and it is 3/4 thick aluminum plate. it does not move at all. we'll know for sure when she gets on the auto-x and run the piss out of it. and,the bolts are really no longer than stock since there are studs through the water pump to the stainless standoffs and then bolts holding the mount to the stainless standoffs.