It's easier to add details and just make the model look better than it's HD counterpart. Reskin the models. Remake the gun holster on barney, redraw his ID tag, give him a radio, give him a little strap around his helmet and stick things up there (cards, smokes, pics, etc, lol). little details like this can improve the model and give it a more realistic feel. Or change the hgrunt heads. Like my av
. (Not mine, BTW, but from the HIT site.) Speaking of HIT (Half-Life improvement team) They might be a good resource for modeling. Google 'em.