I'm not by any means an expert, but in my opinion you won't gain much if any accuracy at 7m with the 1inch difference in barrel length. Having said that, if this gun is for punchings holes in paper and possibly competition shooting, then you might as well go for the longer barrel. Just my .02
Edit: The XD Tactical would be comparable to the Glock 34 as well as many others. I'm sure other people will have more options.