I have an OLD commercial P&P (Quad QSA30A) made in about 2000. It has 3 nozzles and an automatic nozzle changer. A bottom camera was optional, it doesn't have it. It does have flying vision, however. There are line-scan cameras on each nozzle that sights across the part, and it gauges the dimensions and rotation/centering of the part. It does an amazing job on 0.5mm lead pitch parts, placing them within about 0.1mm of perfect, and usually even better than that. It also has a top camera for fiducial detection. It also has servo motors for the Z axis on each nozzle, and places the parts very gently. I do 0603 as my smallest parts, I don't even want to think about 0402!
Jon