I lost all electrical in an Archer.
Of course, day VMC near lots of airports, so didn't exactly panic. The alternator decided to crap out, and (must have been a weak battery) at first the radios became weak, lcd displays flickered, then it all went quiet (the radios). Reduced the electrical and had an uneventful landing. I had only been up for 10 mins, so it happened relatively fast.
In the clag, without knowing the reason (short circuit?, fire to follow? dodgy engine driven fuel pump?) I can see exactly why this driver might want to land asap.
A handheld GPS doesn't keep you right side up (even a Garmin 196 with t&b, AI etc). Handheld radio doesn't keep you from nailing a mountain (even a transceiver with a VOR). If you are ready with these things up and running, then maybe....
I sure wouldn't chance pressing on if I had an out. BUT, I like to think I wouldn't be VFR in IMC......
What I didn't do when I lost the juice was sqwawk 7600. Sort of useless without any power (I was afraid of short circuit, so when I wasn't getting electric power I closed the Master). Still think I should have done it though. Next time.