Does anyone know if the Magpul B.A.D. Lever works correctly on the 15-22?

No it does not work correctly out of the package. It must be re bent.

Magazine is in a slightly different place on the M&P15-22 than the M16. Not sure the utility of this device, you probably inserted the magazine with your left hand. Why not slap the bolt stop with the same hand, it's right there?

-- Chuck

Its biggest advantage comes when you need to lock the bolt to the rear for clearing a malfunction. Traditionally you'd have to press the bolt catch with the left hand and use the charging handle with the right. With the BAD lever the trigger finger can operate the bolt. It does save a fraction of a second during reloads since it's one less movement you need to make.

Useful when time is ticking away and you're in competition or a real right, but for a 15-22 it's either one more toy to add or trying to train a certain method for your centerfire. In my opinion anyway.