gavra_at_work – I agree that there are several different types of chumros. However, I would split them up slightly differently:
The first category would be a chumra due to a lack of clarity of which shita we follow halacha li’maseh. There are several sub-groups to this category: Not relying on a generally accepted kula (for example, cholov stam), or being choshaish for rishonim that the Shulchan Orach/Rema didn’t paskan like (not relying on an eruv).
The second category would be gedarim that may not be halavha, but are there to stop you from being over on the halacha. (Note: this does not include gedarim set up by the Rabbonim, because these are now halacha.)
The third category would be chumros that aren’t really chumros at all, but are things that we feel that Hashem would want us to do.
Your categorization works, but it also leaves out what the results should be, and does not differentiate between accepted “halacha” and what we would call “chumra”.
For example, Rabbainu Tam Teffilin is due to a Safek, and the Shulchan Aruch says only a Big Chassid should wear them, but otherwise it is Ga’ava.
The second category is what worries me, as I agree they should be done, but we have Chazal that tell us what Gedarim we should keep (e.g. playing a musical instrument on shabbos) and those we should not (e.g. not eating meat during the year Zecher L’churban). There has been an explosion of “gedarim” in the past 20ish years which were non existent in the prior generations (e.g. four inches), as well as ignoring the actual gedarim the chachamim created (e.g. Kol Sheino Milamdo).
It has almost created an “Ish HaYashar B’Einav Ya’asee” situation, and that scares me.
The third category I would like an example of what you mean, it seems like you are talking about Naval B’Rishus HaTorah & Darchei Noam, but I’m not sure.