Flex plate question

I am thinking about getting a different torque converter for my externally balanced 440. B&M sells a neutral balanced converter and tells me to use a B&M #10237 flex plate. It is a round plate with a cutout on the edge.
Reading the questions on the Summit website I am not sure it will work. Some say the cutout is for clearance for the converter weights. Some say the cutout is to compensate for the weights and to use a neutral balanced torque converter. I called B&M and the person I spoke with did not really answer my question. Has anybody used this flex plate? What converter did you use? Did you notice any engine vibrations?
Author: fivepoint