Yup. The xten, in my opinion, is lacking in many important ways.
1) Magazines are too small for any 10mm cartridge that outperforms the 40s&w. Any cartridge with a COAL of 2.257-2.260" (within SAAMI spec), and/or a meplat that is over 6.6mm will hang up within the mag tube, possibly/probably causing a failure to feed. Not confidence inspiring to say the least. Large meplat (7.0mm and over) hardcast projectiles will not only create far more friction against the front radiused corners of the tube, they will catch on the mag-catch holes, causing mis-feeds. I've not had this experience with any other pistol I've spent time shooting when the cartridges were loaded to max SAAMI specs.
2) Compared to other reasonably-accurate slide-equiped pistols, the slide is a tad on the light-weight side, so when using a projectile worthy of 10mm power (ala Jeff Cooper's intentions of 200 - 220gr), the slide has 2.23mm of rearward movement before the projectile leaves the barrel. This over-movement provides too much opportunity for barrel movement and inconsistent POI. If the slide was heavier I believe accuracy (consistancy) would improve markedly. I've done detailed dynamic and static analyses and calculations on the many pistols/calibers/projectiles I've had at my disposal, and the numbers clearly bear this problem out -- light-for-projectile slides are not nearly as accurate as properly designed, heavier-weight slides. Also, the slide on my xten has a lot of lateral play compared to any of my other semi-auto pistols, and this may be another reason why my xten just doesn't get the job done with acceptable accurately at 40m and over. Yes, you could try to use a heavier slide spring, but a slide spring doesn't act like appropriate slide mass when more slide-moving resistance is required in the very first millisecond or two after ignition.
Sure, you may be of the opinion that a pistol is merely a very short-range tool to get you to your rifle. What about the scenario that Elisjsha Dicken found himself in at the Greenwood Georgia mall in which he had to take out an ar-wielding would-be mass-murder at 42 yards? Those who have good concealable-pistol accuracy at 50 - 100 yrds likely will be better-abled to save the day in these strange, wrong-is-right/right-is-wrong days. The xten is far from being that accurate, at least in my hands, when compared to my other out-of-the-box stock 10mm handguns that are consistently accurate to at least 120 yrds (even with fmj range ammo) and that I depend upon every day.
3) Sig has adopted a sighting system that makes the target (POI) obscured by the front sight, unlike all other pistols that typically have a POA/POI that is bisected by the front sight. The xten comes with #6 sights front and rear. To make the POA/POI like the other pistols in your collection (so you don't have to relearn your sighting habits) you need to purchase and install #8 sights front and rear. This is an additional $150 if purchasing the same type of sights from Sig.
4) For some reason, Sig determined that the slide lock on their p320 weapons should be placed such that the dominate hand's thumb is in a position that always keeps the lock down when holding the weapon in a firm manner. Sure, if you believe that the slide lock is actually a slide release (as Sig obviously incorrectly believes), when in the LGS you may actually appreciate the control's placement. However when actually operating the weapon with live rounds, you're going to find that it is in the exact wrong position if you're using your thumb as a means of additional grip as when the slide-lock is even slightly touched will not allow the slide to lock open after the last round is fired. Every other semi-auto pistol provides a space for your thumb that is free from inadvertently pressing the slide-lock. The p320 is completely ridiculously designed by supposedly firearm-savvy engineers. It's like they designed it for neophyte hollywood-types who believe the 'slide release' should allow dual-wielding pistoleros to operate their weapons more expediently in their movies ("Underworld," etc?) But even so, if the pistolero doesn't have a good, single-handed grip using her thumb as part of her tight vice-grip, what good is that 'convenient' slide release position if the dang slide doesn't lock back properly?! Absolutely crazy. Any decent pistol-shooter knows how to extend his thumb to actuate a typically-positioned 'slide release' if his non-dominate hand is somehow incapacitated or otherwise engaged in a separate task. At any rate, my slide never locks back properly when using this pistol. I have normal-length thumbs. They're a blessing with any other pistol and an absolute curse with this silly xten.
I've finally made up my mind to loose myself of this xten, even though I really want to like it. It has a nice feel in the hand, the trigger is acceptable out of the box, and it's balance is good for a 5" barrelled pistol. I've put over 600 rounds of many types and brands of ammunition through it. It's works ok with under-performing, lightweight projectile ammo, but for using true, heavier-weight 10mm full-house ammo, it fall flat on it's face. The xten does ok when compare it to a 40S&W pistol. It just does not justify the money, time, and effort that I've put into this weapon trying to make it fit my needs, nor would I trust my life to it.