The hole is to force the piston down off boost to create a gas tight seal. The spring pressure alone is nowhere near enough to push the piston down on part throttle. A light spring is needed for rapid pressure relief when you back off the accelerator.
What I'm saying is the DV+ only has one hole, but OEM uses 4 holes. Make of that what you will, but to me, any deviation away from the OEM design introduces a variable which makes troubleshooting a pain in the neck.
