I faced the same dilemma a little over a year ago except that I was comparing the FNP to the XD
m. The standard XDs in .45 ACP are known to dislike 200 gr. SWCs, a bullet I shoot a lot. I checked the FN forum and found more than a few function problems that steered me towards the XD
m. Customer service was also something of a question in my mind. The XD
m is designed to shoot the 200 gr. SWC and mine functions 100% with those I've shot. For me, the interchangeable back-straps were an ideal feature. I am one of those that believe that the match grade barrel of the XD
m is more than marketing hype. My pistol is match accurate.
I knew that neither pistol's triggers would satisfy me so I wanted the availability of an upgrade with either pistol. I read many high endorsements for the Powder River Precision trigger kit (there are others) for the XD/XD
m, so long story short, I ordered an XD
m along with a Powder River Precision "Match Easy Fit" trigger kit. I installed the kit before taking the pistol to the range, although I dry fired it quite a bit. I have very little take-up, minimal reset and no over-travel. I have a trigger that will rival many custom 1911 triggers. Break is around 4#.
I bought the XD
m sight unseen. I had previous experience with a 5" Tactical in .40 S&W and found the trigger reach a bit short for me so I knew the interchangeable backstraps on the XD
m would be a bonus. I have large hands with long fingers and use the largest backstrap on my XD
m. I shot about 400 rounds with the medium insert installed and found it a tad short. I never have installed the smallest insert but believe that those with smaller hands would have no problem with the trigger reach.
So, I favor the XD over the FNP, but I prefer the XD
m over the XD. The prices are comparable, maybe a little less for the XD
m vs. the FNP. As far as a striker fired system goes, it has a faster lock-time than a hammer fired pistol. That's why so many people favor the Glock. The G-21 was also a consideration as I liked the large grip size but what turns me off of Glocks is that they don't relieve ejection ports and I would have had to buy another barrel to successfully shoot cast lead. So for me, it's the XD
m and I couldn't be more pleased.