Juan Santiago with his red blood cell mechanics work came across as a really careful good scientist. His team have been doing what appears to be useful work on how to measure RBC deformability - useful for many purposes beyond ME/CFS.
Sadly, despite quite a large sample, they didn't find any difference between healthy controls and PwME. He's not ruling out differences but there seems to be a huge amount of variability between individual samples. Santiago suggests that there is a lot of noise, with things like a bit of exercise potentially changing deformability.
I'm thankful that scientists of his quality have applied their expertise to studying ME/CFS. I hope that he'll keep looking - perhaps tracking individuals before, during and after exercise.