I've never used Fireworks but what are it's strong points over Photoshop ? And are their any alternatives to Fireworks ?
I'm going to make a wild guess that one of it's strengths is you can export slices and any desired resolution. In photoshop you can export slices, what I hate and I hope I explain this correctly is if you have a layout of 2000 x 2000 and you create the slice and you want the slice at 125x256 it won't work. I know there is a slice dimensions option but it's just that, for slice dimensions. I find I have to export the slice, re-import it into photoshop and then change the dimensions but I'm going to leave the door open if there is a solution to this.