Well I think it depends on your motivation for the trade. See the problem with the credit spread is your margin of error. If you put on a bear call spread and the stock rallies in your face you could be faced with a steep loss right away. With the backspread when you look at it graphically you have a little bit of time to work with without ever going in the hole. So you could put on the backspread then as it rallies you can re-evaluate the situation and either hold for it to go through the long strike or get out of it with no loss. The bear call spread gives you no breathing room really but you do collect more premium. See, if you are using the backspread because you have a stock where the volatility has exploded but no news has come out then you can put on the spread with very little risk and wait for that pop. If you are doing this on a quiet stock and just hoping that it doesn't move then your credit spread might play out better but still like I said, you have no room for error. The beautiful thing about the backspread is how you can adjust it after you put it on. But I think the backspread works well in a very volatile stock that the mkt is expecting a big move. If you don't know the direction of that move then you don't want to be stuck with a naked call out there. As far as how rare that big move is, well when you have a volatility explosion I would say 80% of the time expect something to happen. That's smart money running in there on some news that hasn't hit the mkt. But your right on the quiet stock, the big move is very rare but then again, I think one of the benefits to putting on a spread is capturing the volatility implosion that occurs on the sold strike.