If you remove the carry handle and replace it with an optic, you should be able to co-witness your optics with your iron sights. It may involve using a rail riser, cantilever, or higher/lower mounts(depending on the scope/optic) to get them on the same plain. I've been lucky with my pdw's flip up irons and a clone eotech. Haven't even needed to adjusted the eotech.
Having the sights at the same level helps your muscle memory. When you raise your weapon, you're always going to bring it up to the same spot. Faster and more precise movements for rapid engagements.
Also, if you have an illuminated sight/ scope/RDS and your battery dies, you can still see your BUIS and not have to stop action pulling it off or replacing the battery.
Alternatively, you could mount a carry handle scope or get a carry handle rail adapter.