Have you tried running it VTA before? Generally for VTA to work well you want a speed density tune vs. MAF tune. While I was working on my X I checked out running VTA without a tune just to see how the car functioned and it chugged at idle and died on me every time. I know others have had different experiences but I wouldn't do it without the correct tune. Our cars seem to do a lot better recirc'd unless you have a specific reason/tune to VTA.
while ill agree that recirc is better for are cars simply because it requires more fiddling to get vta to work well in all situations
as long as the valve is tuned correctly (valve not the car) it will run fine the evo has a maf and map sensor it reads and both and will use both you can see this while logging maf calcs map calcs and load load will switch between the two calcs
problems arise when the valve stays open at idle any hestation that change the vacuum may close the valve, which now changes the length of the intake.
with the valve open at idle the air has like a foot to travel to get to the tb, when the valve suddenly closes the intake track now has the entire licp ic uicp turbo and air box to travel which creates a lot more vacuum and cause the engine to stumble then the vacuum fluctuates which creates a resonance and bam poor idle.
with proper spring pressure and preload a valve can run fine. did it with my cobb valve, synapse trickyer.
valve should stay close at idle and when you rev the car it should open enough to let the air out but not hang open too long