I am looking for opinions from teleconverter users ...

Minolta Maxxum APO 1.4x AF
Tamron Maxxum 1.4x AF
Sigma Maxxum EZ APO 1.4x AF
used with Sigma AF 400mm f5.6

and

Canon Extender 1.4xA
used with Canon FD 400mm f4.5

I would like to here some real life experiences with these or other
teleconverters.