It has been a very long time since I had a custom built system, so I am not familiar with all the BIOS settings. That is something I would love to rectify at some point in the near future by building my own system again. As a graduate student, it has just been more cost effective to get pre-built systems with the bundled bloatware that brings the cost down. :-{
I'm not really sure the difference between S1 and S3 for routine use and reliability, so if someone else could shed some light on that, I would be very grateful.
I led with the above precursor, but to answer, I have read a number of users also speaking of S3 being unpredictable during my time on the forums. I didn't want to say so without first letting you know that I myself know very little about it from firsthand experience.
I did find this:
Standby Explained (S1, S3)