The insert in the middle is the conventional sized grip with the others being a smaller and larger grip than the standard Glock grip. I didn't get the pleasure but our agency did get a chance to T&E one a couple of weeks ago and I am told the smaller grip proved to make a significant improvemt with small framed female shooters and the .40. I guess we will know pretty soon as we will be one of the first agencies getting these and it will be the new Duty gun for the office.
Looking at this picture I would be glad if they stay with the conventional vertical slide serrations on the 4th Gen. I am not into the curved style on the other RTF pistols.
check out the new glock 21 sf rtf 45acp but with the rtf grip and regular slide just picked one up christmas eve so far i love it