Hello,
Because of the Improvements in 1.5 patch, SPQR 6.0 will have diplomats, how this will help the player is yet to be seen, it may help on some trade etc. But over all dont expect Nations your at war with to accept peace like in 1.2. Also trade rights will help some, but because of the size of the map, if its not near one of your cities the trade rights might as well be with the moon. lol
Overall I have been testing diplomacy in SPQR 6.0 and I do like it alot. I think most will, Diplomats will cost more as do assassins and spies. BUt there is 0 turn recruitment on them. Bribing is very hard in 6.0 because of the patch etc. So over all Adding Diplomacy will not hurt the gameplay in SPQR 6.0 like it did in 5.0, infact you may need a little peace just to survive! Of course 6.0 will NOT work with any saved games from 5.0 so please keep that in mind later when its released. But overall it will FEEL like a new game and will play wonderfully and Bug free. ;-)
Lt