I started this thread asking specifically about plumb back valves. Vta valves are purely aesthetic and are probably detrimental to performance.
Ive found that pedal response was better with an aftermakert plumb back valve, less air vented as the valve closes quicker.
edit. Actually , reading over the last few posts it seems ppl jumped to conclusions without reading what I was actually asking... it was never about vta valves... further more, it's not the peak pressure the valve holds, but also the response. Much like 2 turbos with the same power rating, but the behaviour building up can be dramatically different.