Saving machine settings between sessions

[Neale]

My current CNC router is really quite slow. I'm cutting some 3D shapes at the moment which can take about 12 hours, although this is partly because what I'm cutting is fairly fragile and can't support fast or heavy cutting. Because I don't trust the machine to run by itself for long periods (I leave it running to go into the house to make a coffee, but drink the coffee in the garage because I'm not happy to leave it much longer) I pause LinuxCNC and stop the spindle if I need to leave it, say, overnight, until I can recommence. Although I can note the gcode file line number and go back to a specific line, I still can't shut down the control PC because I shall lose my current machine position. No, I don't have home switches, and I'm not sure if those would give sufficient repeatability anyway.
I'm wondering what other people do, and if, say, Mach3 can be configured to save machine position and pick up again from cold as long as the machine hasn't moved. Actually, I'm not absolutely sure that LinuxCNC couldn't do this, although I haven't seen anything about it.
I'm expecting answers along the lines of:
- if you built a decent machine, you would trust it run unsupervised (and that's just one reason I'm building a Mk2);
- if you built a decent machine, you could cut fast enough that you could do a job in a single session (see previous point, but also first sentence above);
I'm still wondering whether to go Mach3 for the Mk2, partly to allow use of an external motion controller and get away from parallel port issues, and occurred to me that this might be another reason.
This question was also prompted by the fact that my PC just stopped during a cut earlier this afternoon and refused to reboot. I blew the dust out, reseated everything, and it rebooted. I've lost the home position anyway, but it started me thinking about controlled shutdown.

Thoughts, comments?