I believe this is very achievable, because the extrusion printing method itself requires the new layer to get compressed somewhat into the previous layer. (If the Z layer steps are not optimized in this way, you can get easy delamination afterwards if the layer-to-layer contact will be minimal.)
That being said, it takes a lot more optimization to get an absolutely solid silicone print. We've sliced open some of our sample prints and there are visible gaps, but they are very evenly distributed. However, the seams are still sealed overall -- so there is very much potential for making silicone pneumatic devices.