Just thought I'd weight in. I like my XD9 and XD40. I like the way the feel in my hand and point. I like the fact that the magazines are dimensionally identical and can be interchanged. Only the witness holes are different. I like the take down much better than the Glock OR Walther P99. The frames are even the same. I take my XD40 to matches so I can swap parts in the event of some failure. I like the better supported case head and the true rifling.
Since production is scored minor, I don't really have a reason to keep my XD40, long term. However, I can't imagine going to a major match (state, regional) without some form of backup. If I want to make a real "go" at competitive shooting, then I'd probably trade the XD40 for a second XD9, as well as purchase some spare parts.