Just bought myself a Carburetor Cleaner and went into action.
I didn't need to remove all pneumatic system as described, only inlet hose above EGR and of course EGR itself. It wasn't that dirty and didn't stuck. But upper part of inlet manifold, where hose is attached to... well, I had something to see there!
Hole was like 1/4 to 1/3 packed up with dirt. I covered bottom holes on EGR valve place to prevent dirt going too deep. With long screwdriver and vacuum cleaner I removed most of dirt, and remains with Carb Cleaner and cloth, wrapped around screwdriver. Estimated quantity of dirt was around 1/2 deciliter at least.
This was the first cleaning ever, on D192T3 engine, 2003, with 144000 km.
One thing I would like to point out: -My EGR valve does not come in two pieces. On mounting holes is obviously riveted together with thin cylinders or some sort. I didn't try to take it apart as it doesn't show any signs of hard moving.
VADIS is not very useful here. It shows only one model of EGR valve for all models and years, and even there is pictured as mounted transversally on engine, rather then longitudinal as it really is.