If they unfriend you because you want to try out a new service...or they could do what I did and unfriend people at LJ and friend them at DW. The confusing part is not everyone keeps the same username...

But if they truly unfriended you in both locations over this...then I think you're better off without them.

But then again I'm not exactly attached to my entire flist just certain people. :) Like the ones I talk with mostly. :)