Ok, so this may be a stupid question, but hey, when I'm about to drop this much money, I think I can afford to ask a stupid question

So I ordered an Eotech 517 from Opticsplanet today, and they called and told me they only had the 516 in stock and it would take them like 10 days just to get in the 517. The dude on the phone said they were "exactly" the same, except the 516 took the CR123 lithium batteries, was a little shorter, costs 10$ more. So first question: is this true? And if so, do these batteries carry some advantage over the normal AA?

So should I stick with the 516 or hold out for the 517??

That certainly isn't the only difference.  With the 516, you'll get a lower 1/3 cowitness without a riser.  The 517 will give you absolute cowitness without a riser and a lower 1/3 cowitness with a riser.  Both have the side buttons and neither is night vision compatible.  Other than batteries and the riser issue, they are the same.

Edit: Never mind, this is wrong.  Both give lower 1/3 cowitness without the riser.  They are identical except for the batteries.

Not correct. The 517 also has an integral 7mm riser. They are the same except for the batteries.

My bad, this is correct.  I actually just talked to my LGS guy today and he told me the 517 didn't have the built-in-riser.  But, EOTech's website says otherwise.

I would think the 517 would be better cause AA batteries are dime a dozen. However I like the smaller 516 gives you more rail space to add back up rear sight, or mangnifier.

With the riser on the 517, you can mount the optic further forward and it will clear the delta ring.

FWIW I would wait and get the AA battery model.

If you plan on going diving. 517 = Submersible to 10 ft, 516 = 33ft

The 517 can use both lithium or AA... 600 hrs. (easy to find AA) or 1000 hrs on lithium like the 516.

So it boils down to submersible depth vs. battery availability they both run 1000 hours on lithium

I went with the 516 because im more concerned with the thing getting wet than being able to find lithium batteries every 1000 hours.

I hate to disappoint, but no EOTech in the history of L3 Communications has lasted 600 hours on one set of AA alkaline batteries. I honestly doubt they'd last 600 on a set of lithium batteries, let alone two sets.

Per EOTECH catalog pg 11. But yeah I'm sure they dont exactly.

And my last waterproof timex rated for 50 m drowned in 10 ft of water :)