I am also 6.1 and the sizing chart I have seen goes up to 6.5. The problem I have is that my weight is on the upper end of the medium scale. So it was either a large or a medium and I was told to get the smaller medium size so I get the full effect of the compression.
They started off fine but stretched after two uses which I don't think is normal. I have read other posts complaining about bad stitching which could cause them to stretch quicker if they are not stitched properly.
Thankfully, the company where they were bought from has agreed to take them back but it has kinda put me off wearing them. I don't want to risk buying the large size coz I think they will be too large for me. Large goes up to 100kg and I am no way near that. My scales put me on 80kg.