Bump, because I really want to know the answer to this one as well.
Having UGC diplomatic missions would really help to reduce the current grind for diplomatic xp. More importantly, some of the best storytelling will involve some non-combat objectives and background material.
On the other hand, having UGC diplomatic missions would reduce the current grind for diplomatic xp. If you get my drift. I'd hate to see a way for diplomatic xp to get farmed with a bunch of gamed fast-click diplomatic missions.
It would be quite nice if, simply, from time to time they take some popular and well tested maps and Cryptic itself chosses and adds ingame rewards for them, chosing the ammount of XP and such involved.
I think XP rewards are going to scale with averages, so, if, for example, a player has just made Commander, well, missions at that level tend to reward players between 200 and 275 XP, so all Com.1 players finishing a UGC mission will get ~238 XP for combat missions, so as not to be an exploit, while RAUH Feds or M.Gen. KDF players will make somewhere between 4-500 XP per mission.
Average rewards for missions of that level seems to be a fair way to go. Where with Diplomacy, we always see reduced XP & Merit rewards +10 DXP, so I think that should hold true for noncombat UGC, preserve the balance, alleviate the "sameness" of the grind without providing an exploit.
I too am curious about the DXP potential here. We KNOW from the Devs that authors will NOT be able to assign mission rewards of any sort (XP value or otherwise), but that the missions are supposed to scale. It would be fantastic if non-combat missions automatically grant some DXP. Even if minimally, say 3-5 points instead of 10? Or similar.
I suppose that ideally, in the future (however far off it might be), part of the Mission Design process might include setting the Mission Type before creating the mission. Combat, Exploration, Diplomatic, etc. Perhaps this could be part of the formula for the mission payout. In other words, by establishing the mission type beforehand, the author identifies which XP type will be used by the Foundry Tool itself to determine payout.
This could be particularly beneficial in the long run, where it was possible to "Fail" a Diplomatic mission for example by attacking a target before reaching a diplomatic solution.
I'd certainly like to hear a Dev response to the OP.