true, if your ventilation in the veg room is strong then it wont hurt the plants, but it will hurt your electric bill. And also its going to
make it harder for you to keep the RH up since you be sucking the heat build up from the HPS.
Personally, I like to have my veg room running on flurecent lights, saves alot on the electric bill. Would rather recomend you putting that hps in the flowering room, maybe put it vertically on one side of the plants, this way a larger part of the plants will get light and you end up with good nugs from head 2 toe. just a tip.