Hi Andy,
I had Botox under GA back in 2008. The worst thing was the enema beforehand as that made me feel sick, but once everything was evacuated I felt normal again.
Yes it did work for me. IIRC there was short-term discomfort afterwards but no pain, and I was worried about larger/harder BMs for a while, so I continued taking lactulose for another 9months after the treatment, very gradually reducing.
I have to wait until mid-May before I get to see the consultant about this AF (again, caused by childbirth), but if he offers me botox again, I will opt for that before more invasive surgery.
HTHs.