I would honestly say there's less people who have completed the Xan questline as there has been people who have completed 'Shut Down the Terminal'.
Perhaps that's personal, in the fact that it's easier for me to complete SDtT vs Arid/Neretva+instances, and I can honestly say I've yet to even finish Neretva on more than 2 of my 9 220s.
At least SDtT is an easy enough barrier to entry by comparison.