There’s going to be some sliding friction from the teeth not following a straight track against the bearing races. Will that wear faster than a chain?

How long will the exposed ball bearings stay clean and smooth facing the spray from the front tire? Even if they get seals.

I think the ratio problem isn’t too bad. It looks bigger than half inch pitch, maybe like the ones in an RC car front wheel, so the spacing of a one tooth shift should be wider than a bearing.