The HL limit used to be 3,000 polyies per model, actually. Only now there's a way to avoid the poly limit, and pretty much even exceed 5,000 if you want to, even with 512x512 meshes. It may very well not be that wise to go that high though, since this -is- a beta, and it could cause some serious probs in-game. i.e. crashes
Especially with people who have ****ty comps. (unlike me)