robho - 1:11 am on Jul 10, 2010 (gmt 0)
It works both ways, would you want visitors to get confused and go to the other site?
Probably depends whether your objective is a throw-away "me too" site, or something you plan to build into a long-term brand.
Personally I would spend the time and money to pick the right domain at the beginning, rather than changing (or being forced to change it) eventually. It'll never be cheaper later.