has anyone used this paper for alt process, more specifically platinum/palladium? If so, do you have any tips (does it need an acid pre-bath, etc.)? I just bought a pack of it after really liking the Awagami Platinum Gampi but finding that it is hard to come by and stupidly expensive (like $10/sheet for a 9x12 inch sheet).
I have not used that particular paper, but I have tried samples of other Awagami papers including some pretty light weight ones. I'm not sure if I tried them with Pt/Pd but I certainly tried them for salted-paper, my main process. All of this was several years ago, so the details are fuzzy in my memory and buried in my notes! As far as I know none of their papers have carbonate buffers so they should not need pre-treatment with acid.
Also, most of the thin Japanese papers I tried are surprisingly strong. They need to be handled with care but are not impossible to work with. My usual working method for most processes is to use multiple trays for processing and to transfer the print from try to tray. With thin papers, I used a single tray and poured solutions into and out of the tray. I made sure the print stuck to the bottom of the tray while pouring solutions out and made sure the paper floated again when new solution was added. This works best with a tray one size larger than the paper as it allows one to avoid wrinkling the paper near the spout when pouring out solutions.
Having said all of that, after testing several Awagami papers, I do not use them in my practice. As you say, they are very expensive and, more importantly, I thought that the paper was taking attention away from the image.
One way to help with costs is to purchase large sheets of paper if they are available and to cut them down yourself. This also gives you more flexibility in sheet size when printing.
I do this with all of the papers I print on routinely. A good source of many papers in large sheets is Acuity Papers, a nice small company. (I have no connection to them, other than as a satisfied customer.)
Acuity does carry some Awagami papers (see:
https://www.acuitypapers.com/category-s/163.htm) but I did not see Platinum Gampi listed. They might special order you paper if you ask.