Leupold Delta Point Pro Red Dot
At this point, I don't think there's any question that red dots are the way of the future. Some folks feel that the future isn't quite here yet, but it's going to happen.
When it comes to red dots, as far as Brimstone Gunsmithing is concerned, there is only one; the Leupold Delta Point Pro. The old standard of the Trijicon RMR is still relevant, and a lot of folks are familiar with them, so lets describe the DP Pro by comparing it straight across with the RMR.
When it comes to red dots, size does matter. Obviously you're not going to mount an EOTech on your carry pistol, so there is such a thing as to big. But the thing is, that red dot hovers over the spot where the gun is pointed, right? So lets imagine that you draw your pistol, or shoulder your rifle, and the gun isn't quite pointed at the target for whatever reason. This situation is not uncommon with pistols when the shooter isn't really familiar with where his/her gun points. So... you draw, you're looking at the target, and from your point of view the frame of the red dot appears to be about six inches 'larger' than the target. Put another way, you can see three inches of 'space' (hopefully your backstop material) between the edges of the target and the edge of the glass. But your presentation was a little off on that draw stroke and your pistol is actually pointing twelve inches to the left of the edge of the target. That is enough of a difference that the dot is 'shinning' off the edge of the glass, and therefore isn't visible in the screen. But it's often a small enough difference that you can't feel it in your grip, so all you know is that there's no dot, and you start waving your gun around trying to find the dot. With practice this goes away, but the larger the screen, the better chance you'll have of finding that dot right away. The Delta Point has a significantly larger screen, without being so big that it's hard to carry or conceal.
One other nice feature of this larger screen. Let's say you fire a round, and during recoil your grip isn't quite what it should be, and the gun cycles and settles back down on target, but it's not exactly lined up like it should be. Let's say the gun is still pointed at the target, but it landed a little to the right. Normally if the sights aren't lined up with your eye, you can't tell where the gun is pointed. But if the gun is pointed at your target, but a little off-line from your eye, this larger screen will still allow you to see the dot on the target, and light a round. Essentially it lets you cheat a little...
The Delta Point, as with most/all micro red dots, uses an LED light source. These means that you only can have a 'dot' rather than a 'cross hair' like on on EOTech (which uses lasers), but it also means that your batteries will last exponentially longer than a laser driven system. For that reason, the RMR batteries last for ever. Often you'll just leave them on and swap out the battery every year or two. The Delta Point takes this a step further by adding motion sensing technology to most of their optics. When at rest for 15 minutes the light turns off, and as soon as you move it even slightly, the light kicks on.
Secondly, the Delta Point has an outstanding battery compartment. On the RMR the battery is in an un-sealed compartment on the bottom of the red dot. This means that it's not waterproof (even with the plate they still leak), and you have to remove the red dot to change the batteries. Not only is this a pain in the butt and can result in you needing to re-zero your gun slightly, but it's also the number one source of stripped screws on these red dots. The Delta Point has a magnetic, spring loaded, waterproof, battery compartment on the top of the red dot. Pull the catch, the compartment springs open, stick the battery to the lid, close, and press the latch. Done. Every single Leupold optic is submerged in a pressurized vat of water to simulate 60 meters for an extended period of time, then inspected, prior to shipping. That includes their scopes.