Another possible consideration is the fact the Pro is set to be Roon Ready soon, according to Wiim, whereas the Mini does not have the required RAM or processing power, as far as I am aware, and will never have Roon Ready status.
I don't use Roon at the moment, but may in the future if I build up a big enough library of downloaded/ripped music.
Also, the option of coax and optical out means I can connect to my AVR as well as my DAC (I don't actually, but might in the future).
I think they are both phenomenal value for money.