Yesterday I finally got my 44 pre-1957 notes back from PMG. They messed around back in March telling me there was a glitch in the system and that they were past the turnaround time and put a rush on them. Well, some US notes I had sent in took 7 days with PMG's FedEx mailing since for some reason they were delayed 3 days in two different cities and took a week to get to me. So since my 44 Thai notes were not shipped a week before I left for the auction in Thailand, I chose to have them held and not take the chance they would not be delivered before I left. So these notes are either new to my collection or replacing a lower graded note.
Having only dealt with US currency grading, I'm not sure how they grade foreign currency, but, to me, it looks like they Under-graded most of them.
I visited Thailand in March & stumbled upon a coin shop while there. I saw no pre-Japanese Intervention notes like P-35a 10 Baht (1939) but the big surprise is the Japanese Intervention notes P-39b 1 Baht in AU58EPQ! The Japanese used notoriously poor paper & you can see the printer's quality looks cartoonish. Thailand is extremely humid so the notes often get mold/damaged easily. I saw a terrible VG example for about $100. I think that P-41 20 Baht & higher denoms are all very rare (from what the dealer told me). P-44a & P-45b are a bit more common but @keemao examples are in excellent shape. The "a" versions of the later 1948 notes are much more common than the "c" & more recent "d" versions. Nice set!