Now for something completely different. Has anyone tried a HRE multi-player game? Each player gains a kingdom of the HRE at the start (the express premise being that whomever gets to play the first emperor creates the kingdoms and doesn't change any laws while those kingdoms are still uncreated - I guess a slightly edited map would work as good), that would make it a 8 player (can you have that many? otherwise two kingdoms for each person) game (Germany, Burgundy, Italy, Bohemia, Bavaria, Lotharingia, Pomerania, Frisia). It could be quite exciting. Including voting for a new emperor between the players. It would also render HRE actually playable.
Which brings up another point. You should be able to tell a vassal to command his own strategic effort in a war; controlling everything from the HRE throne room is fucking silly. Especially when those vassals are kingdoms. Which brings up another point, emperor sliders should be much more difficult to configure than kingdom sliders - more autonomy. If the emperor owns a kingdom that slider over-rules the empire slider within his own kingdom.