The sights might be one factor, but there are others that can come into play. Some guns can shoot a particular load very well, while others will hold a group like a shotgun. Sight height can also come into play, as well as egronomics of the gun for the individual shooter. Personally, as I get older I like the bigger sights since I pick up on them more quickly. For Glocks I like Meprolite or Glock factory night sites. When I went to the police academy I used a Glock 21 for qualification that had only factory sights. When I graduated I put a set of Meprolite sights onto it for patrol work. When I took it to the range I notice the point of impact raised slightly using the same loads I qualified with a few weeks earlier. The reason for this is the dimensions of the Meporlite's are slightly different from the original factory sights. If you like the sights on the Sig and you shoot well with them I would try them on the Glock. It may be that you can focus on them better, as well as picking them up faster for follow up shots.