[Ghazban]

Well, it depends on how much is in the pot, how much the original bet is, how much you plan on raising by, whether or not you can get more money or bluff effectively on the river, and how deep the stacks involved are. Furthermore, you can't guarantee that all the people calling the original bet will also call your raise. One of them could also come over the top (probably the original raiser, but you never know if someone behind him is playing second-hand low). Honestly, I think there are too many variables here to definitely say whether or not its +EV or -EV.