I think he means vacuum piston ones, the VAG piston one is electronic and thus reacts as fast as the diaphragm.
Not quite - all the VAG ones (diagphragm and piston), as well as aftermarket ones such as Forge are all 2-way electronically controlled. There is no vacuum actuation on any 2.0 TFSI valve.
But I'm probably being a tad pedantic - I doubt anyone could actually tell the difference between the two OEM versions (providing they were both functioning A1).
EDIT: for cr@p spelling