I wonder if electroforming a shell of copper or nickel would give the acrylic enough strength to stand up to the heat and pressure. Some detail would be lost but it might work.
As for the polyamide, yes this would work great and I heard that it can even be burned out effectively if one wanted to go down that route. The print lines though, ugg. I guess if one wanted to use it as a master for making a mold it would be ok because one could spend time removing the print lines and carving on it to accentuate the details.
Hmmmm... That just gave me an idea. Lets say one had complex detail that they needed on a piece like a text engraving for example, well one could print the text engraving portion in frosted extreme detail and make it as an inlay to fit exactly into a polyamide base. The acrylic text engraving inlay in this case may be able to hold shape long enough to complete the vulcanizing.
Or how about this. Lets say one used the extreme detail plastic to make a mold and then filled the mold with something that would be far more robust like polyurethane.
Or how about a multi piece mold made from extreme detail that could be used with a wax injector. Given the precision of 3D printing a very nice multipart mold could be made without too much trouble for some types of geometry.