[willy]

I think that you guys are right in a sense, some boats with the notched transom like that are very sea worthy boats, get rid of water almost as fast as it could come in. We all saw that video of the guys in Hawaii playing in the monster waves with the transom like those.
And Mulv is also right that the scuppers in the V20-21 is too small to do the job right if water does get over the wall.
So what is the answer I don't know for sure but my experience has been that for 99 percent of the fishing that I have seen anyone doing the full transom is the way to go and the best of both worlds would be to make scupper about four times the size of what is on our V's. That would be the foshizzle.
For those times you got giant waves swamping the cockpit repeatedly the full notch would be great if it is like the one pictured, but if you have the notch transom with the non-movable knee wall you will have the same problem as a full transom boat without the benefit of the protection it serves.
If the wide open transom (like the one CTT posted) is not over heavy in the stern and rides high with good buoyancy then it would actually be the best overall in a rough sea but would likely be a wet boat for that 99 percent fishing, especially if you fish a lot of rips, inlets etc.
You'll notice most well built small fishing boats(commercial type) have very large scuppers or are open all around with railing, same thing with well built sail boats, 6-12 inch scuppers in the cockpits. Any size wave that comes in just runs out. They also have several inch step over at the bulkheads going forward or down a cuddy or pilot house. Not a inch or two like our V's.
But you will also notice those people also are dressed in high rubber boots and slicks or pants most of the time.
For the majority of the fishing we would ever do with the V's the full transom is probably the best overall with the notch transom/knee wall close behind it.
If you like making long runs off shore with a small boat the open version transom is probably best if the sh!t hits the fan which you will be more at risk of encountering.