Making the supply limit so high makes strategic useless. If you can station 100+ ship/planet you don't need to decide rerouting other forces to defend from other planets or from offensive fleets and also this makes diversions pointless.
An other thing is multiplayer games are mostly played in small maps.
The smaller supply limit forces the player to find the perfect balance between offense and defense, economy and technology to achive victory... better strategy wins.
The other changes are good. The 500% PJI is also in my mod too.