The Holosun (hs515cm) I bought is all of that and mil' spec'. I've used one for years in competition and many thousands of rounds fired and it's worked fine. But it's not my first or even my second of these sights. I like them a lot or I wouldn't have so many of them. Since I'm ignorant about the SIG Romeo sights I can't make a comparison.
I can tell you that I have a buddy who shoots competition with me and he has had his optic quit at least twice while he was shooting a stage that I witnessed. My solar powered optic simply can't unless something inside goes caddywumpus.