I have been shooting and carrying my version of the now ubiquitous Roland Special for about a month. I have put about 500 rounds through it pre-comp, and about 500 more through it complete as the picture shows. Frame is stock Glock 19 gen4 with an Agency Magwell. Slide is an Atom with all stock Glock internals. RMR is 3.5 MOA adjustable, and barrel is KKM with the carver comp.
As a TL;DR at the beginning, I like this gun a lot. The dot took some time to get used to, but I now am picking it up on every drawstroke, and any time difference for the first shot compared to irons has now disappeared. The dot also has made shooting at distance (ie. steel from 50-200 yards) much better. A-zone hits at 50 are easy. The forward serrations of the ATOM slide are very nice to have. I have shot guns with dots that had irons both in front of (like the ATOM), and in the rear of the dot. I have found, for my personally, that it really doesn't matter much. I have yet to have the dot go down, but I have turned it off and used the irons to practice, and having the rear sight in the front has caused no problems, and the timer says a time difference does not exist, so I don't worry about it.
The barrel is probably more accurate than factory, but I have not done enough slowfire to really see the difference. I do my best to stress accuracy, but a precision pistol shooter I am not. The comp is really the new piece for me. Before I got this comp, I had shot maybe 10 rounds though a .38 super open gun about 2-3 years ago, and a 50 round box through Matt's comped Glock 19. I am still waiting to borrow a 34 from a friend to see how big the difference is between the 19 and comp vs. just using a 34 and using the extra length for barrel and slide, but the comp does reduce muzzle rise, and I am faster on target. Rapid fire groups have tightened up, and when my grip is in order I have shot some 2-3 shot strings where I don't see the dot leave the glass.
Shooting at night: I have tried my HST 124s at night, and didn't find the muzzle flash to be serious enough to impact shooting, or sight. When watching from the side, there is noticeable flame coming from both the sides, and the top of the comp, but when behind the gun it hasn't been an issue, granted I have been shooting at static paper only. Those with more practical experience may have more to say about that. In talking with several guys shooting open guns in USPSA, the name of the game is gas volume to get the comp to work. I decided when I bought my stock of HSTs from SGAmmo last week, that I would buy a couple hundred rounds of the infamous 9BP-LE ammo from federal. The purpose of this was to see what the extra pressure of an +P+ round would do when shooting a comped gun. Theoretically, the extra pressure from the gas should work the comp better, and help keep the gun flatter. Me and a friend shot a mag side by side with some HSTs, and there was a bit of a difference. I did feel like the gun was flatter, along with a bit more concussion when shooting the +P+, but that could have been my own bias, as I knew what ammo I was shooting and expected a certain result. Next time we go shoot and have more time, we will load mags for each other so there is no bias, and will have some better, less biased, information.
Overall: This has been my primary carry gun for about a month. I very much enjoy shooting it, and carrying it has not been a problem. I am now completely sold on appendix carry as my default carry method. I still have my strong side holsters, as there are occasions where they are the best option (like when carrying with a suitcoat). I bought an appendix holster with an X300U for both the Glock 19, and a sig 229, and both carry very well. The holsters are top-notch, and I highly recommend them.
I work on the campus that I am a student, and I am regularly in front of a class, so having my gun easily spotted is obviously not a good thing. Even with as big of a gun as this seems to be, I am confident carrying like this, and keeping the gun completely concealed. The roland special has been of great value to me, and it deserves a serious look.