I’m seriously considering a custom melee with 1x 10-52 cassette for road, 160/50T. I tend to do relay bike leg races for half Ironmans with some occasional 65k and centuries. Potential for elevation gains of 2500-5000ft. Currently I have an emonda 2x12 but I’m not really happy with it. It’s always felt off since I got it. Anyway am I crazy for considering this change? Tell me your opinions pros and cons please. I’m a single gal so be nice and talk my language. 
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Moreso than the amount of elevation gain you do in a race, how steep is it? If it’s 4% stretched over a long distance, that’s much easier to manage with a 1X as opposed to climbing at 8% for a long duration.
You would also have the benefit of keeping two chain rings if needed. You could have a 42T & 50T (or whatever configuration you decide on) for courses with a lot of steep climbing.
As a whole, it seems the gear range of 2X is still preferred for road racing for a lot of justifiable reasons, but the simplicity and reliability of 1X is something to consider.
I agree with @Trix8806.
Having used both 1x with wide-range cassettes and 2x setups, I still greatly prefer the closer gears from something like an 11-30 or 11-34 cassette.
Where I live, I could probably get away with a 42 or 44 x 11-34 since we don’t have sustained steep climbing. In that scenario, a 1x could work well, but I’m not sure it’s any better than a 2x setup..
What makes you want a 50 x 10-52 on a road bike? 
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In my head with the bigger cassette I’d still have several gear options for all scenarios with a 1x compared to 2x12.
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When using a 1x 50x52, you’re at a 1:.96 ratio, but Sram does offer a 46x33 crankset that, when paired with a 10-36 cassette, you get a 1:.91 ratio.
Even if you went with Shimano, a 50/34 with an 11-34 cassette has a 1:1 ratio, and with 105, you can get an 11-36 cassette, bringing you down to 1:.94
If you’re looking for a good gear range, 1x isn’t the only option anymore. It works well for MTBs or gravel bikes where your chain is bouncing all over the place, but on the road, I don’t see a solid reason to go that route unless your terrain allows you to still get away with a smaller cassette..
I asked a similar question in the past: 1x curious, let's talk about it (road bikes only)
Since then I ended up buying a the SRAM 48T 1x aero chainring and ran that for a while with my factory 10-33 cassette. It was actually pretty great but I wanted taller gears so I didn’t have to spin as fast at higher speeds. I ended up buying a 52T 1x chainring and ran that for a while, but then I jumped in the deep end and went to the SRAM 56T 1x aero chainring with the new red 10-36 cassette. I live in a mountainous area and I still love it. Every climb is basically a threshold or V02 interval but I’m stronger than ever and descents are very exciting.
If you go to a 50T 1x with 10-52 I’d suggest to try to role-play a bit with your existing setup to see if you’ll be ok with the jumps in the 10-52 cassette. When you’re riding instead of switching 1 gear at a time always switch at least 2 at a time and see if that bothers you. If it seems fine you’ll probably be ok with the 10-52. One thing to also consider – Since you’ll likely need a new rear derailleur anyway you might as well consider the new SRAM XPLR 10-46 cassette & derailleur. The jumps between gears will be a little smaller (at the detriment to a little climbing gear range). This is predicated on the Melee being UDH compatible though.
Here’s a comparison of the gearing with a 50T chainring and 10-52 12spd vs 10-46 13spd. Cadence is across the top of the table. The table shows your MPH at a specific cadence.
I personally like the closer ratios on a 2x system for road use. I can get away with 1x on my MTB’s because I’m never in a constant speed anyway to want that perfect cadence.