Barney,
Essentially the point is other users are also facing this issue. and since I have been able to reproduce same in safe mode its to do with Apple kernel files. Plus 15.4 just came out 4 days back. so there might be other users facing same issue as well.
Till date there seems to be no solution other then reboot and save all work before every sleep
I'm not experiencing any problems and have been running .4 for several months on two very different Macs. I am currently running the .4 release without issues.
I haven't seen any other long-time posters report of problems, nor do I remember seeing anything noted by anyone else in the rumor mills (but, I don't pay much attention to them anymore).
The point is, if you want help with your specific problem, you have to create your own post to focus on your problems specifically.