Hi!
In an attempt to verify by myself if rating inflation is real, I will be participating virtually in this contest from 2015 in roughly 15 minutes (21h05 UTC-3). I invite you to do the same!
I will do this for the next few weeks, and maybe gather some statistics in the end.
UPD: Among 3 participants that I consider very trustworthy, the rating change was very small. (Around +10 for each one). The rating variation was estimated by looking at people with similar original rating that got similar ranking in the contest as well. So this very small sample indicates that rating inflation is negligible.