Never really like Shure's grey flex. I like olive much better though, but it will be a very tight fit over PL-50 so I didn't put them on. Also confirmed: big bi-flange, Comply T100 and Sony Hybrid, Etymotic tri-flanges will all fit.
Anyway, I get a good fit with the stock single flange so I am good. Stock mid foam is just a bit too small.