Was keen to get one of these for a silent-as-possible SFF build. Still am. Sort of.
Why is it so hard to add a few extra dollars to the BOM and put a decent fan with a decent profile in a power supply?
Would I pay $20-30 extra for a small, efficient and quiet supply with a Noctua in it? Why yes, I would!
Or even better, a modular power supply with modular fans. We spend hours tweaking our choice of case fans, but have zero choice when it comes to power supplies. These PS companies are missing some great co-branding/differentiation opportunities....
FWIW, I couldn't be happier with my SX500-LG. I'm using a H100i in a push configuration (blowing the radiator heat outside the case) and the only time the PSU fan turns on is when my GPU heats up. The H100i does an exceptional job of keeping the PSU in silent fanless mode otherwise.
I also don't have any noise issues when the fan does start running. I feel like I'm in the minority here after reading these posts, but there is some hope for you.
Oh I should also add that I replaced the H100i stock fans with Noctuas because they were the loudest thing in my setup. Now my GPU blower is, but overall it's quiet enough for me.