So, I have all three of the RDS referenced in the above two posts. The Shield RMS was the first MRDS that I personally bought. Since several of my peers have used the JPoint as a back-up on both ACOGs and ELCANs, I had confidence in the performance and reliability of the RMS. I used the RMS on my carry gun for about 6 months with zero issues, but in terms of testing the sight had less than 200 rounds of abuse behind it (I admit this is a small amount, but in my defense my EDC gun is simply a compact model of the full-sized gun I use in competition). It transitioned from varying lighting conditions flawlessly, was cross-compatible with all JPoint mounts, and promised to provide me years of service. Then disaster struck.
The day after I ordered a JPoint to use as an offset sight, I switched the RMS to my competition pistol and took it to the range. When it looked like it might rain I threw caution to the wind and trained anyway. After about 50 rounds it began to rain. Like a torrential downpour. Since I was shooting steel, I thought, "fuck it, if it ain't raining..." Less than 50 rounds later the RMS flickered out. Thinking that I shorted the battery, I switched it out with no success so I went home. Then thinking it might have become waterlogged, I submerged it in a bowl of rice for a day and tried again. Thinking that maybe, just maybe my spare battery was bad I went down Wal-Mart and bought a brand new 2032. Still no luck.
At this point, annoyed that I had just bought a new JPoint and was waiting for it to arrive, I decided to write to Shield. To their credit I contacted them with my problem, they gave me an address to mail the sight to (in the UK), and within two weeks sent me a replacement sight. I still have no idea what exactly broke on the original sight. While I was waiting for the replacement sight I broke down and bought an RMR. I haven't thought twice about it. The new RMS is sitting in a drawer waiting to replace my JPoint when it breaks.
Speaking of JPoints breaking. Yes, it is plastic and yes it (like the RMS) uses a plastic-type screen. To the credit of JP Rifles, it you look on their website they will tell you that the JPoint, if being used in a duty capacity, should be considered an expendable item and planned for accordingly. Unfortunately for me, I didn't discover this (or pay close enough attention apparently) until I received my JPoint in the mail.
So, a brief summary: is the Shield RMS or JPoint suitable for hard duty use? Not if you account for the fact that it is expendable and that for the cost of replacing it, you would be better off just buying an RMR and worrying less about it breaking. I do still recommend it as an offset sight or on a competition weapon or in a plinker capacity. And that is all I have to say about that.