Klaus-Dieter was only proposing Q-scale plots for publishing results,
Why this 2pi factor? Why not 1/d or sin(theta)/lambda. During a very brief look at SAXS it seemed at least a few authors disagree about the units, with "s" also appearing sometimes. It was confusing and there was a lot of swearing.
it would indeed be useful for everyone to report on the same scale for comparison. I would personally prefer an (approx) constant density of peaks scale
Depends on the lattice? Cubic patterns look great in old "Q": eg: Announcements 1959 "Tables of Q as a Function of 2theta (1959)" Acta Cryst 12, 421, (1959) ... where Q was 10^4/d^2. 2pi/d just needs a better name than Q? Best, Jon