Ah, thank you!

I use SysRq to REISUB my machine — but I haven't found the SysRq key on Macbook keyboards; and haven't had the nerve to enable SysRq on friend's computers (which I often end up troubleshooting), since I didn't know much about it, what the security implications are, and whether 1 is an advisable value for kernel.sysrq

Those sysctl options could make a big difference; I've wondered about something like that, but assumed the optimal default was built in. Thank you! I'll try tinkering with those values.