Well this is a compact model and the larger grip is just for extended mags. I think it's perfect for its size and all. I can instantly go from a short compact grip to a full size grip after an easy mag change over.

Can you tell that the extension is there holding it (the gap) or does it feel that it fuses together flush?

The extended grip is just something you slide into the extended mag. The extended mag is really just a standard XDM 9 mag with the grip. I still haven't had time to fire it yet. I'll see if I have any feeding problems

Here's what my gun looks like with the new grip extension from Pierce.

http://i71.photobucket.com/albums/i1...1/P8070001.jpg

How did it shoot?

Went to the range last week and it shot pretty well, much better now that I can get a full grip on the smaller mag.

That looks like a fine piece you've gotten yourself Ex. I'm quite a fan of the those magazine bottom extensions myself, they add enough for me to get my pinkie on the gun.

Speaking of XD's though, I'm curious to see how the new XDm 5.25 competition gun will do. It looks pretty nice.
http://www.dawsonprecision.com/images/534-022.jpg