Well... I don't remember but I had about 2 years' worth of comments across 3-4 accounts (I usually change accounts every few years), so about 6-8 years' worth of comments.
Just editing the useful comments doesn't take that long honestly - there were a lot of "hold my axe!" or pun chains that I left as is.
I think reddit is reversing all edits made using powerdeletesuite.
What I did was to sort by comments by top score of all time, and then manually edit the useful ones to paragraphs of gibberish (google "gibberish generator" or something. I left all the snarky comments and low-effort puns alone.
I still don't like the ridiculously big quick toggle icons and the fact that wifi is hidden behind a second layer of quick toggles.
Also I'm not sure about the warranty process, that's always been their weak spot