Recently available online and perhaps of interest
MANNING, SEAN: The Armies of the Teispids and Achaemenids: The Armies of an Ancient World Empire (https://www.bookandsword.com/wp-content/uploads/2023/12/37-2-Manning-web.pdf)
Thank you for that. Always worth reading such papers, but personally I found nothing new in it, and some elements a little surprising, such as no mention of the possibility that the reason the soldiers depicted at Persepolis are not wearing armour is because they are engaged on ceremonial duties, not dressed for campaign. And the whole point of Herodotus' account is that Xerxes' army is not uniform, but equally artistic evidence from specific locations is likely to depict a degree of local uniformity because they do not portray an army (whatever its size) drawn from across the empire.
Thanks, very interesting