To the dev team: Please dont move away from the history on Elective Gavelkind. It is and should stay as hotch-pot, to be equally divided among all elective.
Instead take a look on the road the players can travel to move away from sucession law. The early age should play out as it is, the game will be broken if it is to easy. As loong as the mechanics is explained there will be no confusion on the topic.
There should neither be a easy way to plot our way out of this time era, if there are 3 brothers they ALL inherit by dividing the land on 3. For balance on the elective part, winner takes the capital, end of story.
It is important to stay true to history, and it is important that earlier we can start, thus harder it should be. If you are set within 100 years, everything AFTER cm expansion will be a cakewalk. We have time to figure and plan ourself out of gavelkind, game will be broken if the first 50 years will be about rush-blobbing your nabours. What challenge is it to it if we start 800+ with a strong base?
Concubines is for the broken wife who does not leave you a son. Or you can marry an old hag for alliance and take a concubine for breeding. Instead start the game with options on old hags with bonds to add this to the mix. The game is already very easy to beat. Rap up the bugs who actually are bugs, gavelkind who divide equally amongst electives will serve its purpose.
As mention over, maybe look into how the player can move himself away from this type of crown on sucession. Some wants to be king, some wants to be a republic while others a elective in gavelkind. Its all about playing the hand you get dealt, with earlier start date we have more than enough time to solve it. If you overdo this and make it serve against its own purpose, most of the time you restore wanted real within a couple of decades.
Starting the game as a single landed [insert whatever] tells you its on hard difficulty. This factor is one of the very reason why it is hard, and it should as the old ways was hard.
So please Paradox, dont nerf history. Instead make more roads for the future.