Of course but it works the other way round too. Leicester won the league in large part because of Vardy's goals, he was integral to that. All of those guys you listed above got in and around the same level of league goals that Giroud has in his Arsenal career, so nothing like Vardy. The only real comparable one is Adebayor for one season and I think we can look at the two players attitude on the pitch and see the difference immediately. Adebayor has never been wanting for ability, but his big-headed approach and greed ruined his career. Vardy plays one way and I don't think either of us can see that changing. For me it all comes down to if he can fit into our style or if Wenger is trying to change how we play.
What I said is Vardy is a safer bet, not a safe bet. We are comparing the two strikers and the risk is higher with Janssen, you can agree to that. As I said, buying both would be ideal given how cheap the Dutch kid appears to be but I don't see it as a disaster with we miss out on a gamble. We've spent long enough punting on young unknowns.