My experience of hardcore in BC2 - it's great for getting kills with sniper rifles. But damned hard to tell friend or foe. I got in the habit of spotting people just so I'd get an audio queue if it's an enemy I'm looking at. At the same time, sometimes I'd get so sick of not getting many kills and getting sniped every time I sneezed that I would just start teamkilling until I got auto-kicked. At least that way I felt I could kill someone!
I enjoyed BF3's hardcore when flying because I found it to be an increased challenge. Plus it's easy to tell friend/foe in the air. But on the ground? I think I'd start going mad and unibomber C4-ing everyone.
Holding the fort on old games that play the same as the new ones, minus the $400 price tag.