i think it'd be a great april fool's joke if they switched back to the fucked up pre-decimalization british currency and made you deal with farthings and thruppence and such.
you could even do it where, like, Echoes, Hinterland Scrip, and the Khanate all use different subdivisions. so like in London you use echoes, pence, farthings, and shillings, but upriver it's all bob and thruppence and bingos
the khanate is already "you are throwing around fistfuls of disparate coins because every group there issues its own currency and you don't quite understand the exchange rates involved", which is very funny