i have a pretty big thumb, so it squeeze it too hard so I can't use it for longer than ~10 minutes. On the other hand tight fit means it really becomes a continuation of my own finger -- and it really convenient to play both chords and single string sections, almost like with the finger.
It sounds pretty close as 2mm thick dunlop ultex (at least for my ears, i'm just a beginner), but more convenient... If only it would be a little bit bigger to squeeze a little less...!