I do appreciate you pointing this difference out though, because it does mean that folks will have $600 (or $830) tied up in this from day 1 and not from day 31.
One possible problem with withdraw later is that you're subjected to 2.5% conversion fee if you're not withdraw to US bank account. In the end some international user will need to pay PayPal about $15 to get refund.
I do appreciate you pointing this difference out though, because it does mean that folks will have $600 (or $830) tied up in this from day 1 and not from day 31.