Bottom out bumpers

Depending on the density, it can limit. But you are talking about 1-2mm maybe. I remember fluid Focus posting something I think where their bump still was almost flat.

Yup they will reduce your travel around a few of mm, and your ohlins bumper will compress most of the way down. Its stiffer than most but they are quite good, when they are too soft they don't absorb enough energy which gets transferred to your frame and thats really bad. So they are kind of supposed to prevent you reaching the very end of the travel because its impossible to stop it compressing at the very last fraction of a mm in a smooth way that wouldn't feel harsh. You really shouldn't and don't need to be using those last few mm very often, if ever. So its not a problem and things feel a lot better if you use a tiny bit less stroke in a controlled way than every last fraction of a mm with a harsh end to it