That specific technique would only really be applicable if you were trying to hire someone to fill a purely support role - you would need a different task if you were looking for a developer. I have found the latter to be a little hit-and-miss, as it depends whether or not your developer is in a comfortable environment. If he is used to a different IDE, it would only take a matter of days to get up to speed on how it worked, but a rival candidate who is already used to that IDE would have a massive advantage, not just in speed, but also knock-on effects in other areas.