Not quite sure what the argument is any more but........
If your still running MAF then it makes it more important to run a re-circ than if your running BAR MAP, air thats entered the system i.e gone through the MAF has now been metered (which is what the MAF does along with other things) and is in the 'system'
'System' means from MAF to combustion chamber, if you now dump that metered air to atmosphere i.e atmospheric bov it upsets the fueling that the ecu just applied to that metered air, if however you dump the air back into the system hey presto fueling is still correct and you should have a sweater running motor!
Ive just replaced a forged dump valve on my 02 plate with the stock item, it feels miles better! pulls cleaner through the range, spools better after changing gear etc etc

 

im deffo gonna get back to my stock dv then, as everyone on here is in agreement that the car runs/performs better.

 

Mine has the Prodrive pack on, but as an example changing gear in third at 3k actually raised the revs to 4k without your foot on the accelerater! obviously the fuel went rich once the bov vented, almost perfect now with the re-circ but not quite

 

You'll get better fuel economy (not boosting against a partially closed throttle on a cruise) and faster responce (the turbo free wheels with recirc valve open faster than it will be trying to boost against a partially closed throttle), also boost will build quicker after a gearchange as the turbo stays spinning faster with the valve open than it does boosting against the almost closed throttle.

Simon