Open Borders also have an effect on Tourism. So they have an extra relevance they didn't have before.Personally, I'd love for closed borders to have *some* negative impact on both caravans & missionaries-even if it can't stop them altogether (either that or move Open Borders to an earlier tech ;-) ). Without such a system, then I fear that Open Borders become greatly downgraded. I'd add a similar view in regards to embassies. Embassies should improve the abilities of both Missionaries & Caravans IMHO.