I've been using -v to try trace my random wake issues.

I've tracked a possible cause - the GFX card not waking up properly. To that end, i've removed the EFI string for my GFX card and got it working via a DSDT patch instead, which means I can send a wake notification to it on an acpi wake, which should fix it if it is indeed the error. It'll be a few days before I've used it enough to see if it's a fix or not though.