All of the cheap dots are garbage. Even the top dollar military grade stuff isn't the ultimate solution (Aimpoint/EOtech) ...they have their issues too. I've seen plenty first hand.
For me, the best solution is to stick with irons. You don't have to turn those on. They rarely, if ever, break. They stay zeroed. Don't need batteries. Won't fail unexpectedly.
I love the XS sights. Either the tritium stripe or the tritium dot front post. At the ranges a dot is useful at, these will do just as well. Trust me, I know all about dots being faster. I have an Aimpoint. Not aligning sights is faster. But how much? It isn't nearly as much of a difference for most people. You still have to get your eye behind the optic and shoulder the rifle somewhat if you expect to have semi-decent shooting form to produce a hit. You can have that dot aligned in a bizarre stance, but that stance won't be ideal for proper shooting and shots do get pulled up down or to the sides. When using the XS sights, so long as you're looking through the rear sight, whatever the front sight post is covering is getting hit. It's very fast. Again, this is from a self-defense perspective. We're talking vast majority of confrontations occuring inside of 25 yards.
The trade off for me is a no-brainer. The very slight decrease in speed is an easy trade off for the time wasted deploying an electronic optic and any potential risk of it not working, having a dead battery or whatever else. If you can anticipate trouble, then that isn't a concern with a dot. You have all the time you want to flip open the lens covers and turn that dot on to the perfect intensity level and go at at it. In the middle of the night being awoken by an intruder and being in a stupor from be shocked awake isn't the time to be fumbling around with optics. That's just my opinion. The newer Aimpoints can be left on continuously. You can't do that with an EOtech.
If I'm expecting trouble - then it means trouble isn't immediately in my face. I have a little more time and distance to work with. Maybe a hurricane disaster zone. A riot. Or something of that nature. For that, I have an ACOG. I can hold my ground and deal with threats at a distance. Again, I'm not so sure any threat will present itself as such from beyond 25 yards, or maybe even 50 yards. I don't envision a group of armed thugs brandishing weapons from 120 yards down the street heading my way to require that I roll up the window and open fire. That's fantasy land stuff.
I'm not so sure about any of that happening. Which is why the 25 to 50 yard max defensive rifle is the ideal doctrine in my opinion. Unfortunately, a lot of people get really worked up by the internet and all this gear and have pieced together actual defensive rifles that would be better served in Fallujah, rather than anything that they would realistically face at home.
I know that you didn't specifically ask about self-defense outlook, but you did mention that you had a concern about BUIS incase the optic fails. That implies this rifle may be put to serious duty.
Save up for a quality optic like an Aimpoint, and then still don't trust it and have BUIS. If you cannot afford the Aimpoint, it is in my strong opinion that irons are superior to any cheap dot out there. Cheap dots are more trouble than they are worth. Like other's have said. They lose zero, break, or chew up batteries very fast. Rather than give you some type of advantage, they only bring the potential for failure and create a lot of liability. Cheap dots are toys for the range. Nothing more.
