xd fighting pistol - magazines?
If you want to designate a gun your "fighting gun" (as opposed, I guess, to a 'plinking' gun, 'concealed carry' gun, 'target gun' or 'hunting gun') then I would think the first concern would be durability and reliability. Which brings me to my XD45 experience.
I'm what marketing experts call an "early adopter" - which means I have a bad habit of buying the "beta" version of everything that comes out. The second handgun I ever bought was one of the first XD45 pistols to come out. My experience: for maybe a thousand rounds it was an AWESOME gun. Tack driver accurate, comfy to shoot, reliable, felt better in my hand than a Glock 21 and had a fully ramped/supported barrel and it held 14 rounds of 45 ACP ammunition which at the time I felt was the "Only" fighting round. (I talked to a lot of old timers who had an emotional attachment to .45.)
Then the magazines started to deform - they would bulge out right behind the top round, maybe from the round bouncing against the rim of the mag during recoil, and as the deformity became more pronounced feeding suffered. Springfield Armory replaced them. Life was beautiful again for many more hundreds of rounds (I shot ALOT back then) but the new mags deformed, slowly but surely. SA replaced them again. Even with new mags, though, feeding suffered. I sent the gun in to SA. They recut the locking block, I think they said? The gun never shot as accurately after that, and with tears in my eyes I sold it. Used the money to put a Sig on layaway.
Springfield Armory, mind, is still an excellent company. I have one of their 1911s and it has been a joy to shoot. I covet their M1a rifles (can't afford one) and their customer service is prompt and efficient. I still don't have a hi-cap .45 in my collection, which I regret, but if I ever buy another XD it will be a 9mm. These days I rely more on the Sig p220 carry that I bought with a down payment from the sale of the XD. If you have a lot of magazines to rotate, I guess the XD .45 is fine. And they may have fixed that problem with the mags by now. But if you keep it, keep a lot of replacement mags and reserve a few for carry/social work, and exempt those mags from heavy, repeated range sessions. If you decide to go with some other gun than the XD as your "fighting gun" go with an older, time tested design. Let the manufacturer work out any bugs and implement any necessary recalls to their new, innovative designs before you spend your money on a new gun.
Or using it as a club w/o breaking apart.