I've used pretty much every type of "combo sight" option on the market (top riding red, top riding irons, side mount red, side irons, optics with built in irons, flip magnifiers, QD mounts & flip sights, etc). Angled mounts are FAR superior to scope-riding mounts. I put my Magpuls on top of my PEPR for a week, tried it a few times, and confirmed it's a terrible idea. Red dots on top can work, marginally, but irons up top are plain dumb. You have no cheek weld to be able to align the sights quickly, and your sight radius is shorter than a pistol! It's slow and imprecise. Irons hung on the side with 45degree mounts can work, red dots are better since your eye position and cheek weld are slightly compromised, but irons on top are a no go.
That picture doesn't make sense to me. Guy has a ton of money sunk into that rig, but he's foolish enough to put the irons on top, instead of realizing he's just as fast and would be more accurate to put the irons on the rails and make use of the Quick Detach feature of the mount he bought to swap between them. Mall ninja schitt right there in my book.
Best option for a no-drill dual sight system is an angled mount red dot on the far side of your scope (port side for righty), second best is angled irons mounted on receiver and hand guard. Top riding irons is the worst option - period.
It's an aluminum tube, it's really ok if you D&T to add rails, whether it's for sights or lights.
Two suggestions in a row for bad ideas (gas block mounted light and scope mounted irons) is starting to seem more like troll behavior than honest questions...