Interesting thread I started here. My comparison between the XDs and the Shield was based on the fact that they are so close in size. There are a lot of choices out there when it comes to small 9mm/40 calibre pistols, not so many in 45acp. S&W did a great job with the Shield and it's sales reflect it's popularity. They priced it relatively low which made it even more appealing, cudos to S&W.
What is appealing to many of us with the XDs is the fact that it's a 45 in the same size package. It's a well made quality pistol that is well designed and executed. I find it to be comfortable to shoot and very accurate, and I wouldn't be a bit suprised if S&W follows with a micro 45 in the near future.