Go take a look at the EOTechs as well as the Trijicons, before you spend your money.
The Aimpoints are awesome, don't get me wrong - but the dot sometimes visually blurs for those with eye issues.
This is something that you'll only find out from "behind the gun." Typically, when it comes to the final choice between these non-magnified "red dot"/"reflex" sights, the end-choice becomes one of user-preference, as any of these three manufacturers truly are top-shelf.
If you Googled "dot moa," you'll find that the 4MOA versus 2MOA debate has been ongoing, and likely will never stop.
Some feel that the 4MOA starts to really limit the AR at ~300 yards/meters or so, as it would cover up approx. 12 inches of the target - others feel that it is still very realistic, and that that capability can be better exploited with the optional 3x magnifiers to help with target-ID at-distance.
To get a better "feel" for this for now, without even going to the range, here's an illustration made by Aimpoint, using a hog as the backdrop:
And this is a decent depiction, on an old AR15.com thread - the pertinent pictures appear towards the end of the thread:http://www.ar15.com/archive/topic.html? ... 8&t=498770
Dot intensity can also come into play. Turn up the brightness/intensity, and the dot can "fuzz out" (visually, to you, the shooter) towards its edges. This is why you'll see, even at dynamic classes, people adjusting their dot intensity on-the-fly. Also, remember that when you engage your white-light, you may visually "wash-out" the dot, and this may affect how you set your chosen sight and store it (with respect to battery life), too.
I honestly feel that aside from selecting a system (i.e. Aimpoint vs. Trijicon vs. EOTech) that better suits *YOUR* eyes, the other biggest consideration should be how you plan to employ the firearm. At anything less than 200 yards or so, you're going to be just fine with virtually any of these optics, but at greater than that distance, you may well desire an intermediate optic, such as a 1-4x variable, instead.
Considerations such as battery-life/usage as well as switchgear should also come into play in your decision process.
In terms of mounting, the big difference is the absolute versus "lower 1/3rd" co-witness of your (backup) iron-sights. The following video (not mine) offers a great explanation of the difference with these two:http://www.youtube.com/watch?v=qj3NY2jwDEo
Graphically, this these two choices are represented by:
And with respect to the Larue mounts:
^ This is *SORTA* what you can expect.
The RIGHT side "LT660" depiction is accurate for lower 1/3rd co-witness on an AR, but the LEFT side caption is better suited as a depiction of the Larue LT751, which provides proper absolute co-witness on standard ARs (on Larue Tactical's website, you'll see that they've specifically cautioned that the LT660HK will not provide proper absolute co-witness with a standard AR, and is instead specifically designed for the HK-416). Larue's revised illustration is shown here:
In terms of the T-1/H-1 distinction, like CADguy
said, the big differences are the nigh-vision (NV) capability with the T-1 that's lacking in the H-1, as well as the water-seal of the T-1. In a recent thread on M4C.net, Mr. Larry Vickers reaffirmed the H-1 for civilian use:http://www.m4carbine.net/showthread.php?t=123189
- as you do save significant coin, with the H-1 versus the V-1.
With regard to mounts, the top-tier ones are all very well-made, and plenty durable enough.
Larue's name often pops up because they're a known-quantity: especially if you want quick-detach capability, you'll want a mount that will come back on the gun as close to zero as possible, and when you're paying for the Larues, you're paying for that very important capability.
However, if you're just looking for a non-quick-detach mount, you can again save significant money - Larue's VFZ option usually takes abut $20-$25 off the price of their Q/D mounts, and Daniel Defense also offers a highly-regarded Aimpoint Micro mount that is among the lightest available.