I'm pretty sure that any difference in accuracy would be due to minute variances from one individual barrel to the next. I have yet to read a reasonable explanation for why a longer barrel would be any more intrinsically accurate than a shorter one...but I've read a ton of comments from people who assume that be so. If you're shooting iron sights, a longer barrel will be easier to shoot more accurately due to the longer sight radius, but "easier to shoot accurately" is not the same as "more accurate"...it just helps you be more accurate.
I'vs shot both lengths of T1x and I personally prefer the longer barrel to the shorter, just like the balance better. Honestly, about the biggest difference was likely the noticeable decrease in muzzle blast with the longer barrel...I like using subsonics in it, or better yet in my iron-sighted Brno (slightly longer barrel), and shooting without earpro.