Meh, the XDs is thinner, more pocketable, with a better trigger/better sights and in a better caliber. AND it doesn't have the stupid safety.
Do you own a XD 3"? Or have handled one?
It doesn't exactly have an overall advantage in size & weight to the new Shield (the XD 3" retains the thick and chunky profile), although it does have a magazine capacity advantage. Maybe the single stack XD will be better?
As far as the safety issue, the XD has the grip safety, and that pivoting loaded chamber indicator (similar to Ruger's indicator, which means more parts that have to function during feeding).
If S&W has managed to create a safety with increased resistance to the original M&P option, then it shouldn't be a problem for proper handling, manipulation & usage. I won't be able to compare it to the BG380's safety until I get one on the bench, though.
I'm curious to see how the new enhanced M&P-type trigger does, myself. The original specs for the M&P called for an acceptable +/- 2 lbs tolerance for the 6 1/2 lb trigger in the 9/.40/.457 (the .45 is about half a pound heavier). The XD specs call for a trigger in the subcompact with an acceptable variance of 5.5-7.7 lbs (slightly more than a +/- 2 lbs tolerance), so it's not like the XD's trigger is going to be much different.
If I can't get one for T&E any time soon, I might just order one, anyway, being familair with the M&P platform (as an owner and armorer). I'm due for a M&P armorer recert later this year, and I hope to get the armorer info for the new Shield in the near future.
I suspect this new S&W will create an increasing amount of market attention, even with the existing smallish compact & subcompact 9/.40's already available.
My first inclination is to try it in 9mm, as I have more .40's than 9's at the moment.