Each babe should be considered, it may not be right for some. It sounds like your LO is pretty happy having something to suck on, after his feeding needs have been met. My DD had tongue tie and despite the various issues we have, I don't feel in any way that her pacifier use hindered anything. It soothed her. She eventually found her fingers and still sucks her middle two fingers to this day (22 mo). My son self weaned from the pacifier at 8mo.
The breastfeeding doctor who clipped my DD's tongue only recommended soothies or gumdrop pacifiers because the shape encourages tongue formation to mimic nursing. I will only use that brand.
For my third baby coming in September, I'd offer one if baby seemed to suck a lot and was nursing well. However, at this point, I'm also ok with fingers (except the added germs). I think the point you introduced it was good - 4 weeks. Its also a good time to try a bottle, if you will ever want someone else to occasionally feed him.
Regarding ear infections, at least in our case, my son never had one until he was 3 (and only one time, pretty minor) and my DD had one at around a year and a half. Also only once.
That said, I agree with the pp about watching pacifiers with your supply and any growth spurts.
Follow Mothering