I read somewhere that playing and making moves otb is better than online for improvement. Is this true?
I play most (>95%) of my games online, and when I play with a real board, I find a bit difficult to translate positions I already played and the visual pattern matching of tactical situations takes longer. Not to look at the board then, helps a bit.
So, I think, when you prepare for a board tournament, or something like this, preparing on a real board will help. When you only play online all the time, it doesn't matter.