I’m remiss in not responding sooner but disabling HIPM completely cured the problem with the Sandforce controller for me.
It’s been a few weeks since I made the change and my SSD hasn’t frozen once since then. Before it used to freeze with the drive light on solid for about a minute roughly once an hour. Now life is sweet.
I’d recommend trying this first for anyone who has any issues with SSDs hanging, freezing or stuttering with a Sandforce 2281 controller.
Thanks DrLucky.