Just a note on the finish, all .45ACP XDs have the melonite finish.
I've got a Service (4in) .40smith and a Tactical (5in) .45acp. I like the Tactical better for it's longer sight radius, standard full length guide rod, and because it just flat out shoots better than the Service. The Service feels better balanced when unloaded though, but that nose heavy feeling of the Tactical also helps reduce muzzle flip (my Tactical feels really well balanced to me with a full magazine).