Which RDS?
Trijicon RMR 06 (Adjustable 3.25 MoA red dot)
That’s my preference for a full size pistol, based both on extensive market research and from owning and using two of them for the past three and a half years. See links below. I have a third RMR 07 on a Glock 17 I rarely use, and a Shield RMS milled on my 9mm Shield slide because it has a smaller footprint for the narrower slide. Four total. All milled. I’m committed. I estimate I have researched over 500 hours on this topic. I have roughly 4,000 rounds through my RDS pistols over the last four and a half years.
My first RDS was the RMR 07 with the 6.5 MoA adjustable red dot. It came on a used, milled M&P FS 9mm. I found the larger dot occluded too much of more distant targets, and RDS are wonderful for longer range shots with aging eyes like mine. It also was more difficult for 10 yard sighting in as it was often bigger than the center of my targets. The larger dot is no easier to “find”. I bought an 06 and like it better.
The dot is in your window because you are gripping and pointing in correctly, not because it is big. The small dot is plenty visible. Because it is adjustable for brightness, you can go from the nominal ~3 MoA size to a blooming dot at the brightest setting that is probably closer to 5 MoA.
I have not used any of the other light options in an RDS. I like simple, and for me that’s an adjustable RMR ‘06. I’ve heard some good things about the new small Holosun RDS, but they have not been out long, had some teething problems, and are hard to find. Interestingly, it has the same footprint as the RMR. I wonder why?
There is no more robust sight on the market than the Trij. This is in part because of their patented top window reverse curve which transfers shock down the sides of the frame instead of into the lens. No one else (except for cheap counterfeit Chinese knockoffs) can use this design. The v2 models have resolved some minor circuitry issues with v1 models. These are what every other RDS aspires to be like. If you are going to put your life on the line in a LEO capacity 40 hours a week, you do not want to compromise with substandard components and systems.
The Trij sits lower than many. This makes it easier to use and to cowitness, and if you are serious about duty use, you need robust and BUIS co-witness. It also has the most widely used milled footprint, even though you have the longer CORE slot that will require using a mounting plate which raises the sight and degrades the strength of the mounting because the screws are shorter. I’m not a fan of generic mounting systems for RDS. This is not an area for compromise, IMO. I choose not to use CORE, MOS, L-brackets, etc. Want it right, permanent, reliable? Mill it.
Buy once, cry once. This new sighting system is a serious, modern upgrade to a fighting pistol. With a proper introduction, the learning curve for an experienced shooter is short and the benefits of increased speed and accuracy become apparent quickly. There are lots of ways to cut corners and costs, but you sacrifice robustness, reliability and longevity.
Now, if you are not yet committed and really just experimenting with the RDS concept, you can go the cheaper route. You may be handicapping yourself though. Then you might miss the real benefits. There all kinds of ways bottom feeders have come up with to get a semblance of a red dot sighting system on a pistol. It can be done for a couple hundred dollars. That will give you a range toy. It can be done for $400-500 and you will have a serviceable system, but it will not be as robust and dependable over long term, rough use as paying top dollar for the system everyone else tries to emulate.
http://docs.wixstatic.com/ugd/7dc128_c8da57977a8c4b53903192fa603fce6f.pdf (Long white paper, but worthwhile. Check out Aaron’s videos where he destroys RDS’s and ends up recommending RMR’s)
GABE SUAREZ BLOG SI has been a leader in RDS sighting for 10 years. RMR is all they recommend.
Tactical Training Courses | Military Training for Civilians John is knowledgeable, experienced and very competent. Reccomends RMR’s. Check out his RDS videos.
American Rifleman | Shooter’s Tips: Learning the Red Dot
I could give you a few more links, but the same conclusions would just be repeated. I’m sorry if I’ve offended others who have different opinions and budgets, but there is a real difference between a range toy and a life-protecting machine.