While 502s, 503s and load speeds have improved a lot after the gluster migration and for me at least don't pose much of a problem, I have noticed that some users have complained that they still do occur for them at some points. I did get a 502 myself one of these days.
A lot of work has already been done and as I said things are largely improved but even more needs to be done as this is clearly the most important issue for users (as demonstrated by the survey and discussions).