Stacking can’t happen on raw files directly, even in Helicon. The raw files have to be converted to RGB format of some sort before the stacking algorithms can do their thing and once demosaiced and stacked, it can’t be turned back into what your camera would call a raw file. According to Helicon, they can convert on the fly (demosaic, etc) using Adobe then stack and save the stacked RGB image (high quality TIFF) as either a straight TIFF (they recommend this) or a DNG (using the converted, stacked TIFF).
That's correct. Part of the Focus stacking workflow is resizing and aligning/registering of the image slices. For that, it's easier that they are already demosaiced. So sooner or later, the Raw source images will be no longer Raw. That the output file can be wrapped in a DNG wrapper doesn't make it Raw again.
So I guess my long winded point is sending a series of high quality TIFFs that you have control over from C1 and stacking those should be on par with Helicon doing the conversion for you.
I disagree. The C1 Raw conversions are of higher quality (higher resolution and fewer artifacts) than a straight Adobe demosaicing. C1 offers additional features like Dust removal with LCCs which is a heaven sent for Focus-stacking, and the LCCs capability of neutralizing Light Fall-off and vignetting is also helpful because we are going to blend images after resizing them, so the vignetting (and local exposure) would be different in each slice.
So TIFFs coming from C1 would have higher quality, allowing to achieve higher quality Focus-Stacks, with less need to post-process for error correction. The Plugin is not a game changer, but it does make life a little easier.
Cheers,
Bart