I agree with your point that this season is a lot more OP than the last. But, complaining won't really get you any where.
There are signs at the spawn that tell you you're not allowed to use more than two pieces of diamond armour. However, you are allowed to use more than two pieces if you're going to fight another player with three or more pieces of diamond armour.
The new rule of not being allowed to wear more than two pieces of diamond armour has been working pretty well. So far I've only come across one player who has broken that rule. This rule has brought in tons of new players.
I like KitPvP 5.0 and 6.0 equally. Yes, 6.0 is a lot more OP. I feel like removing the custom enchantments would bring back some of the old players and bring in some new ones. It'd also restore the vanilla PvP aspect. The server's become more of an OPKitPvP server more than anything. If you have full protection 3 diamond armour, sharpness 5 strength 1 sword, and with speed 2, jump boost 3, and all that other stuff, there's a very small chance you'll be killed by anyone any time soon. In my opinion, 6.0 would be a lot better if the custom enchantments were removed. I don't like them but I don't hate them.
Lastly, I noticed in the videos you linked that you were lagging pretty bad. Honestly, I'm pretty sure it's only you. I don't lag that bad, nor do my friends. Yeah, the server will lag from time to time, no server is completely lag free. But, I'm 100% sure not everyone has been lagging as bad as you.