I wonder if the "access your data for all sites" is really needed. This is the reason I won't use the add-on, which seems to be the best.
I would like it if the author offered also a simplified version not being able to spy on sensitive (eg. banking) data. (The option "Only if unsuccessful" and resubmission of the data, mentioned in the description, aren't critical for most cases.)
Just to be clear: I don't suspect anything evil, but the possibility still exists that after an update such "function" will be added, for example when the author loses control over his development system.