my experience has been that people forget the dash and where they need to put it. why give your comp your traffic?
I recently purchased a two keyword domain name (dot com). It revolves around the Ruby programming language. As I like the hyphen for this particular area, I actually ended purchasing a number of domain names where I've reversed the keywords AND not included the hyphens. All bases are covered, from a naming point of view. I will develop the hyphen version of the name and the others will have re-directs in place.
In this instance, the debate whether a hypen is useless or not is irrelevant.