In my opinion the exp you can get from playing FFA is very low compared to other gamemodes like eggwars where you can get 250 exp per 1 win. Thats a lot. So much in fact that almost all of the highest exp players are eggwars players. I think that FFA gives the least exp out of any gamemode and increasing the exp you gain from it would balance the experience system more. I played FFA for a while now and i gain about 150-200 kills (150-200 exp) per 1 hour of playing which is far less than what you can get from other gamemodes. Skywars games last about 2-4 mins on average and can give you 125 exp. Eggwars game can be even faster and it gives you 250 exp. I would personally say that this could help balance the experience system a little bit. I personally would say that changing it to 10 exp per kill would be ideal.