I got my bearing buddies a few years ago, and the first time I topped them up, disaster...
The hole in the bearing buddy, which grease comes out of to indicate the bearing is full... the first time I did it, does not work!!!
Instead, the grease blew the back seal. Clearly the spring mechanics needs re-engineering.
I have since replaced the back seal and do not rely on that hole indicator at all. After years of experience, I only pump maybe once or twice worth of grease, say every 5 or 6 trips, that seems to work for me. It's too bad no one could offer such simple advice the first time round.
They haven't failed me and I guess you do have peace of mind knowing for sure there's enough grease in there, as opposed to a non bearing mate.