Ah yes, gun p*rn! Really digging those RMRs - the holosun looks great but i don't think it's quite high enough to co-witness with my BUIS - and DI - Now I have something to research. Cheers, thanks CGNers.
Why do you need it to co-witness. They're back-up sights not clutter up your dot sight picture sights. If you have a decent quality dot sight BUIS are pointless unless you really like shooting with irons.
What if the battery goes dead? Change it.
What if my optic goes down? Send it in for warranty, no one is shooting back at you so no life lost.
If you're thought pattern is focused on SHTF or WROL zombie apocalypse preparation then you should definitely not be looking at anything under $400 for a dot sight and I would say an Aimpoint PRO would be the cheapest sight I would buy. If you want magnification then I would keep the budget over $600. A Bushnell anything or Vortex anything is not going to be my choice of optic if I ever think my life may rely on it some day.
On topic, my FX-9 is in the mail (should be here Monday or Tuesday) and I think I'll be stealing my Aimpoint T-1 (and magnifier) from my 9mm AR. Might break the bank for some but there's not many better choices for a rifle that will only be used inside 200 yards (more likely never past 100 yards).
Battery lasts for a couple years even if left on all the time. They're built like a tank, I watched a video of them torture testing one and even after dropping it out of a helicopter, running it over with a truck and generally treating it as poorly as possible it was still working.
It all depends on your eyes and intended use though. Some guys who suffer from astigmatism have a hard time with dot sights. I'm one of them and the dot on cheap sights kinda stretches out into an oval when I look through them, this still happens on the expensive ones but I don't find it as bad. I have the Aimpoint T-1 and a Bushnell whatever -25 they are called and even though they look similar on the outside the Bushnell ended up on my 22LR dedicated AR upper, it's definitely a POS compared to the Aimpoint.
Also depends on what you want to do with it. If you want to do accuracy testing off a bench at 50 or 100 yards you probably want some magnification like a 1-4x or 1-6x but if it's about light weight, mobility, and reliability at CQB type ranges then a high quality dot sight can't be beat.
Search the EE before buying, I've bought some very nice glass for some very good prices, you just have to be patient and check back regularly until the right deal pops up then pounce on it before someone beats you to it. The good deals go fast, the guys asking $10 less than retail end up sitting on them.