Dragging this thread up from the depths, to contribute the following two tests by Fire-4-effect and covered by Recoil -
http://www.recoilweb.com/aftermarket...ng-127282.html
http://www.recoilweb.com/fire-4-effe...ts-127423.html
My take away here is that ammunition choice makes a big difference with Glock aftermarket barrels, more so than might be expected compared to other platforms (e.g., 1911).