I wonder if the S1 dimensions have changed slightly since mine was made? I measure 22" L X 15" W on both the S1 and VDH 23# wings. Regardless, not much of a practical difference.Regarding the S1 dimensions vs the VDH wing, that's probably true. I Think maybe it's just the shape that makes it appear as though the S1 is longer.
The S1 ships with their remote deflate on the elbow, but will a standard elbow still fit on their bladder flange? Not that I would seek to replace that intentionally, only because I'm "removed" from quick/easy service (as stated earlier)...just in case the stock elbow were to fail for whatever reason. Beyond that, their inflator and corrugated look std.
I can confirm VDH and DGX elbows are interchangeable and standard/universal fit vs proprietary, as mentioned by others.