Instead of increasing number of free slots with every tier, how about decreasing them instead? People will trade safe slots for base cooldown, build area and reclaim difficulty. If a person has a t3-4 land claim he is not a newbie anymore, if someone thinks it is smart to stay in t1 he/she will be raided pretty easily once someone realises that he has good stuff. But of course it will work if claims are not invincible. But in general with this safe storage you forget about one thing - people can create multiple accounts (even if you need to pay for a game several times) and make as much safe storage as they want which ruins the whole PVP idea (or simply cooperate and even 20 slots per person is a lot in this case). Just make a PVE server with a PVP zone and leave PVP servers free from all of these nonsense, so you will not need to please everyone because it's impossible.