In particular, let's talk about the recall and what they do to your gun.
Without having taken it apart and mic'd every part before returning it, all I can tell they have done for sure is to drill the grip safety for a non-functional roll pin. I assume the pin is simply the easiest way anyone could figure to let those in the know determine at a glance if a given XD-S has seen the recall fairies or not. It's ugly, but not so ugly that I'd give up the gun.
What I suspect was done was to install a different sear that is either slightly longer or that has a slightly different engagement angle. That, however, is purely conjecture on my part. (I'd love to hear about anyone who knows for sure what was done. Springfield has been very secretive on that point.) My gun never had any of the noted problems, but I decided that it would go back any way. "Rather safe than sorry", and all that.
I have heard some complain that their gun came back with a horrible trigger. While I haven't been able to get to the range (Thank you, Weather Control), I have dry fired it and measured it with a trigger pull scale against a post recall example from the safe. My original averages at 6.5 lb. over 5 tries. The post-recall gun averages 7 lb. over 5 tries; both measured on an RCBS Military Trigger Pull Scale. That is a bit light for a scale meant to measure in double digits. A 8 oz. - 8 lb. Wheeler scale is on order; I plan on repeating the test with it.
Unless I got really lucky, I don't think my trigger is substantially different from what it was when it left. Still, I think some research into lightening them both up a bit may be in order.
Edit 3/31/2014: Wheeler scale in hand, I've repeated the above tests. The original gun averages a 6 lb pull over 5 tries; the post recall gun averages 6.5 lbs. So the RCBS scale, which is not really meant for this sort of thing, actually did a credible job, being off only 1/2 pound on each. Still going to be looking into trigger lightening for both when I get some spare time.