This hasn't been confirmed.
if you're basing it off a website or advertisemant saying "exclusive" that can mean that early access is exclusive to this pack, that's how it goes with most games.
Wasn't it said somewhere that there were five pistols in the game? And there are seven, counting the pre-order pistols. Plus it says everywhere that they are exclusive. Then again, I've also read that they aren't. Anyway, no way to know at this point, but it sounds like they're exclusive to me. Either way, I'm sure they won't make too big of a difference. We'll just have to wait and see.
So in regards to what you're both saying, should I just go with a skin pack? Because that Doom armor is looking pretty legit. And if all I'm paying for is an exclusive skin then I'd at least like to stay flashy.
Edit: I didn't even know the psycho pack came with a pistol. I'll need to look at it again.
Psycho back comes with the http://brink.wikia.com/wiki/Caesar_Revolver, and there will be the http://brink.wikia.com/wiki/Ritchie_Revolver in the regular game. Again, they should presumably be similar, or perhaps even identical in stats.
I'm just going to trust that the game will be well balanced, so I'd say get whatever pre-order pack you like best; if you really like the Doom pack, go for it!