except it is (almost) infinitely better compared to bound armor, quantum suits, kami robes, while costing about the same resource and time investment, which absolutely kills all endgame diversity
Here's the thing though, as with any mod, it's only good if you know the mod. Personally I am still clueless about the mod, and I assume a lot of people are the same. A lot of people stick to what they know, like I would go for KAMI, even though I hate the new TC stuff, because I know what it does.
Or maybe Bound Armour, if I feel like it.
But I wouldn't have ever known about DA armour being OP until reading this post, as I don't know the mod. It's like the Springboards mod that is in the pack. I will mess with it eventually, the cheaper it is, the earlier I will give it a go.
You're thinking about 1.6.4 rapiers. This is 1.7.10 we're talking about, they have since been nerfed significantly.
Rapiers work exactly the same in both 1.6 and 1.7, unless I am missing something. Rapiers bypass all armour which extends itemArmor, but nothing that extends IArmor (or whatever it is called) So vanilla armour = bypass -> Manasteel armour = safe, just because of how they are registered.
The problem is that you end up with a pack that has one viable set of endgame armor, everything else is a joke at best. I played Monster quite a lot and this was not the case there.
Kitchensink or not, I think rebalancing to encourage playstyle diversity shouldn't be dismissed just like that.
I don't want to sound like an a*** here. But if you want to rebalance it, do it yourself.
Everyone has their own vision of "balance". To me balanced is being able to nullify all damage to the player, and 1 hit any mob (including boss mobs) but have to spend a massive amount of resources on anything to automate stuff. This is because I hate mobs, I like peaceful mode - don't judge, but a lot of servers I play on/host seem to like the idea of mobs being enabled, so you need to please both parties.
Whereas other people hate grinding resources, so they will make dirt-diamond sort of recipes, but add stuff like lycanites mobs, to make you die a lot.
And if all else fails, just don't use mod/disable it on your server. A server will always be balanced to how a server host sees fit, so if that means it deters players from joining because EnderIO has been made to require Enderium instead of Vibrant Alloy (because they they think EIO is OP) then that's their choice.
If you are a server host, you get to make the rules, if not all you can do is ask the server owner to disable it, and hope they see stuff the same way as you do.