SBR's are their own issue due to size, kind of like running a J-frame with a speedloader, some changes are required.
For a severe case of switch/sightology, at one point during my time in the Air Force on more or less a daily basis (I switched between regular rifleman, grenadier and machine gunner as needed, sometimes daily) my issued M4 had three sets of iron sights (Front/Matech, leaf and quadrant), M68 CCO (Aimpoint), two types of IR sight (PEQ-2 and IR laser on the quadrant sight) with a paddle and a tape switch respectively, and a Surefire in a LaRue LT606-1 on the left with a clicky-switch. Toss in the M203 with it's own firing system underneath the gun....
And I spent pretty much 12 hrs per day five days per week running this stuff and I'd still get a mental pause remembering WTF I was doing if it'd been a few days since I'd had an M203. Since normally BUIS/Surefire/PEQ2 was the only thing on the rifle.
Simple is good. Scope, light, irons, sling. PRACTICE.
edit 1:
With lights, 200 is the minimum these days if you're starting out new. I've used 60, 65 and 90 lumens and realistically inside one room they get the job done. 200 is better for big rooms (over bedroom size) and outdoors. The 500 lumen is insanely spectacular and what I wish I'd had in 2006. I very nearly shot one of my own guys in 2006 and 65 lumens was enough to ID him at 2 yards range, but 500 for sweeping the (very crowded and dark) exterior objective would have been nicer.
The Fury single-stage with standard tailcap in a LT606-1 would be my personal choice these days. When I update my arrangement for duty use in a few months, that's what I'm going to (from my old, reliable and trusted G-3 at 90 lumens).
Edit 2:
sergeant i rode out while contemplating employment options with his department with had a handheld Fury (500l) I had E2D (120l). We stop and light up a carful of interesting types. I zap them with the E2D at about 10 yards and they knew I was lighting up one guy, the splash sort of illuminated the rest.
Sergeant lights his Fury and all four occupants straight-up thought they were being abducted by aliens....