I bench in Nike Romaleos. I never would have thought it would make a difference either, but I actually get a slightly better setup that way. I was benching after squatting and didn't want to waste time changing shoes, it turned out that I can arch a bit more and it gives me more leg drive.
At the same time, if I didn't already own a pair of squat shoes I wouldn't even consider buying them just to bench in. If you think it will help you significantly then buying a used pair is a good idea.