Hi @Compizfox, I had to read up a bit on this first - no, it is not supported at the moment, all inputs are converted to 8bit images, I should probably document that.
I will look into a 16 bit pipeline eventually, I see someone was trying it a few years back (GitHub - dankamongmen/stitcher16: driver for opencv 16-bit stitching) and faced some issues. Feel free to add a feature request in the GitHub repo.