Many manufacturers are using their LM90 data for chips on spec sheets, not actual fixture life so 50K hours may not actually be true. And when you drop below 90 percent output, there is no lamp to change, but the whole fixture.
Remember LEDs from 4 years ago? Blurple and SUPER Expensive. Think about what will be here in 4 years. Do you want to be left holding the bag?
Light in the UV range is proving to be valuable in THC production. The best strains in the world evolved in geographies that have the highest amount of UV. UV LEDs are self destructive and will shorten the life of the fixture if used in an array.
Fixture Weight and Fans-
LED Fixtures can be heavy because of the the amount of Aluminum it takes to cool the chips. If fans are used to reduce weight, they become a common mode of failure.
The up front costs for fixtures are still 3 to 5x what a proven HPS is. Even with rebates, the expense is still very high to gamble on an investment.