Steve Voigt
Derek,
I appreciate you bringing up the topic and laying your cards on the table. As a maker of wooden planes, I am obviously biased, so that's my disclaimer. All the same, a couple comments are in order.
First, I have a bone to pick with how you frame the issue. You define a "premium, custom" plane exclusively as an infill or metal-bodied plane. Raney did the same thing in an article that someone recently reposted on Sawmill creek. I think this is very unfair. Wooden plane makers build planes one at a time or in small batches; they are every bit as custom as the metal planes. They are made to very high standards, so they are every bit as "premium" or "high end" as the infills, even if the price tag is lower.
Second, I disagree with how you lump metal Stanley planes in with "woodies" as being "lower mass." A Stanley jack is roughly twice the weight of a beech jack: the difference is huge. The only "low mass" planes are woodies: metal planes are either heavy (Stanley), really heavy (modern copies of Stanley), or extremely heavy (infills and related).
As to the issue of which is preferable: it has to be framed in terms of the work one does. If one is merely smoothing off the ripples left by an expensive combo machine like you use, then it doesn't matter that much. But if one is doing heavy work, it matters a lot. I would suggest a simple formula: the ideal weight is inversely proportional to the amount of physical labor required. Try flattening a large table top with a no.5 followed by no.8, then try the same with vintage beech jack and try planes. I think there is no comparison, none. Though I will close by reiterating that I am biased on the topic.