Can offer an opposing anecdote. I have an ASRock EP2C602-4L/D16, loaded with tons of RAM, hard drives and PCIe cards running a bunch of VMs (some with GPU passthrough) and it's been 100% stable. Plus their support has been awesome -- I had an issue with a bent pin and they did a complete motherboard check for me for free, then threw a bunch of SATA cables in the box when they sent it back.
Having said that, they're one of the smaller manufacturers, and it wouldn't surprise me if they're still in the process of getting on top of some of the issues that inevitably come up with a new platform.
It also wouldn't surprise me if GP got a lemon. It can happen with any manufacturer.
As it is, though, I'm a very happy customer of theirs.
I've run into at least one annoying firmware bug on every desktop motherboard I've used in the past decade, including a flagship product from ASUS. Nobody's perfect or even close to it. The two ASRock boards I have in use at the moment don't seem to be any worse than the two ASUS boards I'm using.
Having said that, they're one of the smaller manufacturers, and it wouldn't surprise me if they're still in the process of getting on top of some of the issues that inevitably come up with a new platform.
It also wouldn't surprise me if GP got a lemon. It can happen with any manufacturer.
As it is, though, I'm a very happy customer of theirs.