The experiences that actual users of Performer AFB copies on this forum and on chevytalk have been positive:https://www.chevytalk.org/fusionbb/showtopic.php?tid/362448/
Here's an example from chevytalk:
"I love my Edelbrock #1406 , been on my 56 Bel-air for about 17 years with NO problems at all.
I had it freshened up two years ago , not because it needed it but because I just wanted to keep running good without any problems."
I picked that example because he's had his for the exact same length of time I've had mine, 17 years, and in that extended period of time both his and mine worked perfectly and required no fixing. I did learn in private communication with Jon that as the AFB changed ownership from Carter to Federal Mogul to Edelbrock there was a modification in the accelerator pump system. But that and the differences in metering rods are the only differences I've been able to discover. Thanks Jon!