I put them on a few months back and have only just remembered that I put them on. Tuning stays in seemingly permanently. Just set up and forget.
I think an added bonus is that my tuning experience has become much smoother. E.G in one band I have a mid tuning for the snare, and for all other projects I need to tighten it up. Previously I'd have to tune each lug, then fine tune to make sure each is in tune with the others.
Now this second step is unnecessary, just a 1/4 turn all the way round and it's perfectly in tune.
I wouldn't put much thought in to comments to the effect of "too expensive for washers with rubber". When you consider how effective they are, the comment doesn't hold much weight.