My overload when I fell off was grocery shopping in two pannier bags.
When I leaned the bike over to dismount the weight seemed to skew the front wheel up and sideways, depositing me onto the ground.
I felt and probably looked stupid, not least because my tin of baked beans rolled gently into the gutter.
A touring load might have been lighter, but it seemed to me the amount of weight I had could have been carried safely spread across four smaller pannier bags.
I've never tried front ones, but they always appear to carry the weight in a reassuringly low position.
My ideal tourer would have rack mounts on the front fork to at least give me the option.