This seems like something that must have been discussed here before but I couldn't turn anything up searching.
My "first line" set of gouges are from Thompson, which are made from "A-11" powdered metal (probably using that terminology wrong). All other lathe tools I've used are M2 HSS, most of them inexpensive. I got started with Thompson tools from a recommendation from a turning board; I've been very satisfied with the Thompson tools, but can't really claim that I've done careful comparisons to assess the asserted longer edge life. Not doubting it, just saying I don't really have anything objective to point to.
My observation from reading boards is that virtually every maker of "non-economy" lathe tools has its fans. That could be taken to mean there isn't much difference among decent quality lathe tools, or it could suggest that confirmation bias (the innate desire to believe our choices are good ones) is strong among turners. . .or some of each.
I have a friend (no really, it's a real person) who bought my old lathe and has Thompson tools as a result of my input. He's been reading about M42 tools having greater ability to take an edge than powdered metal (not sure it's a good idea to lump powdered metals together as though they were one thing), while having greater edge retention than M2 (not saying either part is necessarily true, but there are those that make the claims).
So, I'm interested in the collective wisdom/experience here as to where M42 tools lie in the pantheon of lathe tools. If a more specific context is necessary, let's say bowl gouges. I'm asking in the context of "all other things being equal", so this is just about the steel, not the grind or flute shape. Subjective opinions are fine (since that's all most of us have), but I'm super interested in anything quantitative (sorry, my day job is in research, I can't help myself).
Thanks for any input.
Dave