There are a number of good answers here and I am intrigued, as always, by the perspective that each person acquires along with knowledge. It enriches any definition and moreso than if only one person gave all the right answers.

Given similar carbon content and similar heat treatment that is correct for the types of steel being used, the only difference will be the aesthetic. That matches Joed's comment about grain size. As TBS and Bill S have mentioned, cost vs. quality will be based on experience and talent. Shaving performance will depend on honing, bevel and all the other parts of the razor that make it a working tool. If the steel is good and all the other factors are good, so will be the razor.

My pattern welded stuff are all carbon steels. Stainless steels are not impossible for pattern welded blades (Norris, Thomas). Strangely enough Damasteel is a sintered powder metallurgical product made from stain resistant steels. Layers in Damasteel are layers of powder, not laminated bars or strip steel. Some of us have yet to let go of "old" Manah Really old stuff was crucible cast steel and not layered at all (wootz, ukku, bulat).

I got some stuff done this weekend that is a san mai billet. There is a high carbon core with outside scales that are pattern welded. It will have "very good guts" and good heat treatment. I know I can get it sharp and Randy or Lynn could really get it sharp and it will shave. But it could be boring and not ring anybody's bell.

It takes a lot of work and I'm still sore a couple days later. It would have been much easier to make a blade from only the high carbon middle. Not nearly as much fun though, or dangerous and risky because it might not have worked and all that would have been wasted. But when it does, it really sings....

Just more stuff to know. The question was right on.