Make it 5x xp on every skill on HCIM. If HCIM has same xp rate as iron man, there's basically no point playing it. And no boosts like none. If you don't want to play "hardcore" you can always play normal iron man to benefit from boosts etc. HCIM should be a challenge and it's not meant for everyone.
And one last thing. No one dies while pvming like cmon. So at least make the xp rates lower.