Zak, I may have used the wrong term
When I said "flatter shooting", I'm not talking about the bullet drop but the amount of muzzle flip. Of course, a pistol with minimal muzzel flip and a really fast slide is able to be shot faster than a slower recoiling gun with lots of flip. A XD .45 is going to be slower and flip a lot more than a properly tuned .40, which is what we mostly see in Limited. However, I do agree with you that Limited 10 might be a better choice for the .45 XD than production. There you'll find a combination of single stack guns with long 10 round magazines, Limited guns with only ten rounds, and stock guns like the XD.