I hit the range and decided to post a quick range report, shot a 100, two hand freestyle, fairly quickly (around a 1-2 seconds in between each shot) using the two G19's I have swapped barrels into.
Above was shot with my EDC Gen4 G19 w/ S3F match barrel with Trijicon HD sights using 115gr Fiocchi 9mm at 25 yards. I hate to say that I threw the top ring shots, but it looks like I did. Looks like I have to adjust my sights a little bit with this new barrel and/or I have to just break it in, but an 81 is not bad though not great. I remember reading elsewhere on various forums that sometimes when swapping to a new barrel (especially a match barrel) you should swap out your slide lock. Seeing as how I have that fancy match grade slide lock a member on M4carbine.net sent me I figured its not worth doing on this EDC G19. I will continue to document its accuracy and see if it shifts after several hundred/thousands of rounds.
Above was shot with a Gen3 G19 w/ Barsto barrel with modified Ameriglo Defoor Tritium night sights using 115gr Fiocchi 9mm at 25 yards. I called the 7 ring shot when I let it fly. The Gen3 G19 is otherwise completely OEM, sans barrel and sights. So an 89 at first shooting is not too bad. I bet if I fired slower I could probably get in the mid 90's with this setup, especially if I added a negative/minus connector to it like my EDC G19 has.
Bonus! While at the range I saw this beauty sitting in the case...
What is it? An Witness Elite Gold Team in .45 - check out that charging handle. Thing is bad-ass!