Hi Greg--welcome to the forum!
My feeling is with the shear number of molding planes one still sees from that period, many were cut with them.
In general, moldings are hand cut the same way, using the same/similar tools today as then. And that would be with all three categories of tools you list. I think in part it is going to come down to the shop and what they had available.
For myself, I use all three depending on the size of the molding to make. For small, more delicate or curved sections of moldings, I use scratchstock. I also use them for cleaning up larger, more complex moldings, especially if there is a bit of tearout.
For moderately sized moldings, I use one of a few molding planes I have. But for yet larger profiles, the H&Rs come into their own--even if it is in conjunction with other profiled molders.
The couple books I have from about the same period are of larger, more known cabinet makers and a single tool seller. So their experience may not be the same for lesser known or rural makers. There is very little documentation I have ever heard about concerning makers in general as to the tools actually in use. The Gabriel inventory of the period, though, may well give an insight as to the volume of such tools sold.
This is a great topic--one dear to me. A great way to kick off what I hope are future postings from you.
Take care, Mike