I'd try to optimize a Warforged Juggernaut, simply for the entertainment.
That would be fun. And they can pick up life sense too. (they do end up with con: - don't they?)
Wicked feat.
Nope, they keep their constitution score. It makes them rather unique, which is why I like them. There are tons of ways to get immunities to mind-affecting and ability damage/drain (aka Undead/Construct-style immunities), but what I enjoy about Warforged is the part where I'm ACTUALLY a Construct.
Mind-Flayers? Fuck ya! Even if I fail my save against the mind blast (regular warforged aren't immune to mind-affecting out of the box) what are you going to do? Polish my cranial unit with your spittle?
Monsters that want to swallow you? Even if they are willing to eat me (They probably are even though I neither taste nor smell like anything they normally eat) they're probably going to pick me LAST after they've eaten the rest of my party, in which case I would have gotten my unappetizing ass out of there 4 rounds ago.
Monsters that in some way want to eat/steal your essence? Same deal as with the swallowers, dirty jokes aside (AND irrelevant!)
Warforged are probably one of my favorite races if not my favorite, for as many flavor reasons as technical ones.
If they go Juggernaut, take Warforged immunity feats, or find many of the other ways to get all those gorgeous immunities, they're actually better off keeping the con score. They get a bonus to con, which means they'll often have more HP than their con-less cousins, and they'll have a better fort save (Construct type gets all bad saves) for the things that can still force them to make one (Spells and such that specifically target constructs and undead usually give a will save, but occasionally a fort save. It's the obscure shit that breaks builds. Also Disintegrate is not on many lists of immunities since it's not necromancy or a death effect, but having a bad fort save sucks when your opponent specialized in Disintegrate). Oh, and they can still run.
Speaking of running, it's worth mentioning that you can't. There are all kinds of ways to kill most builds, but a lot of builds can just run away. If someone makes something that can get to you and beat you (And chase you if you run away), you might find it an unpleasant surprise that you're incapable of simply RUNNING away. You lose the ability to use the Run action when you have no con score. It may seem irrelevant, until the only thing between you and your final death is the difference between you and your foe's move speed.