I run the fab defense polymer flip ups on my Evo that co-witness with my red dot on a medium riser. I think they were a little cheaper than the magpul MBUS. The FDs are also a little smaller profile than the MBUS.
I like the FD front sight as it doesn't need a tool, just has a thumbwheel. But the magpul does use a std. front post which can be swapped with an aftermarket post like a KNS crosshair. Biggest difference is the FDs aren't spring loaded, they just have a friction lock. So while it's fun to 'POP' the magpuls up, the FDs are quiet, and if dropped, would probably fold before breaking, and can't be 'accidentally' deployed.
I also have a set of Troy flip ups with the DOA rear sight, hands down my favorite but pricey for back up sights. They're on my SHTF rifle which I mainly run irons but wanted flip ups for a compact scope on a QD mount.