Yeah I've seen far, far too many LED failures occurring for me to even think about LED's standing a chance against MV regarding life expectancy. This includes
street lights. MV and HPS are both my personal favorites, especially since they last longer than the Metal Halide Cobras.
As much as I like Metal Halide Cobras, they are absolutely abysmal in terms of life expectancy. Metal Halides do not last long in Cobras, and I've seen recent
proof of this with the ones we have here.

Makes sense, standard “universal burn” metal halides don’t last very long at a horizontal position, any horizontal mount fixture, such as a cobra head, wall pack, or a shoebox, will cut the MH lamp’s lifespan from 10,000 hours down to 6,000. Nearly half the life. Mercury and HPS lights don’t care about the orientation.

They only achieve the 10,000 hours if used vertically (as in a post top, recessed can, high bay, or low bay). Metal halide lamps in general don’t last very long if they’re burned horizontal.

I get why MH wasn’t widely used on streets. I can’t imagine being an electrical technician always replacing the MH bulbs in high mast fixtures even if the fixtures can be lowered.

The only superior thing to Metal halide compared to the sodium was the color and CRI, which is why I even prefer MH. Everything else about HPS was better. The only benefit of MH compared to MV was better color and light quality, as well as better efficiency and CRI. Everything else about MV was better (no explosions, less premature failures).

Newer MH bulbs are also all junk, so no wonder they’re failing. Modern metal halide bulbs are known for being junk. Even reputable brands are now garbage products. The big name brands don’t make HID bulbs anymore. For a while Philips probe start metal halide bulbs were just rebranded Venture Lighting products.

PSMH was a bit better in terms of longevity and efficiency compared to pulse start, but they didn’t last as long as HPS and they tended to explode at EOL. Ceramic metal halide was expensive and not as long lasting as HPS. CMH would be expensive to maintain. That’s why Quartz metal halide was used instead. They were cheaper to run. Chicago, IL, who experimented with CMH cobra heads, experienced MANY premature failures with them. The electronic ballasts in the fixtures used failed frequently.

Universal burning 175W and 250W QMH have a rated life of 7,500 hrs when run horizontally (10,000 hrs vertically). Yep, they're a low performer, but the Philips Allstart CMH retrofit lamps for those systems have a rated life of 20,000 hrs plus, and they don't have near the depreciation issues. Same with 70W/C98, 100W/C90 and 150W/C102 CMH lamps.
Around four years ago, I installed several modified ITT Series 13's at a relative's house using 70W and 150W CMH lamps. The lamps are still going strong, with virtually no depreciation and the arc-tubes are still white.

Depends on the brand. GE ones have a rated life of 6,000 if burned horizontally (I often use GE bulbs as examples), I believe Sylvanias are 7,500. Not sure why there’s a difference.