I'd say no to the imprisonment if you do poorly as a diplomat with one exception. First, let me say why I would not want imprisonment. That is because you have diplomatic immunity, something that should be quite serious. Yes, that means you can spend about 5 gold and even call your host realm all the bad names in your vocabulary. Yeah? So? You're a diplomat. Now why would this make it better?
That's because the ONE exception is if an Expelled Diplomats treaty is in effect. Not only can you get imprisoned for traveling through the realm, but if you so much as try to talk to a group of minor nobility and your tongue gets tied or is anything less than polished silver, your hosts would be all to happy too turn you into the authorities. That would give such a treaty more weight than it does already, because in its current form, all Expelled Diplomats does is allow you to capture a diplomat like any other normal noble. Even if diplomats gained immunity from capture eventually (They don't right now), it's not that big a deal since the capture chances are variable already and a clever player knows how to dodge patrols.
