I'm signing up for a couple of public mailing lists to test how the clients help me handle the firehose of potentially-relevant emails.
For years now, I've used GMail exclusively for public lists, because the conversation view maps really well to how I like to scan most lists - I like to see what new threads have started, and only read individual messages if the topic is interesting. I also tend to look at a thread if someone smart has weighed in, so if a client helps me pick that out, it's good.
In GMail, it only shows three or so of the people in any thread, so I have resorted to filters that star any thread where smart people are talking. I don't love that solution, though, since I also use stars to manually flag something as important, and I'd rather not mix things up.
I've signed up for one low-traffic list (PyObjC-dev) and one higher-traffic list (LLVM-dev), since different traffic levels are different problems. A really high-traffic list can really test a client's filtering and thread display design.
Both of these lists are Mailman lists, which is a very broadly used system and it's what I'm used to. I'm open to hearing about other kinds of lists with different features that might change things, though - leave a comment.
For now I'm starting with digests off, which I like because I prefer to see things by thread instead of by date. Some clients do unpack digests automatically, so I might test that out sometime, but I think that a client should just control when it shows you bulk mail instead of just asking the list to only send it once a day.
I'll report here as the traffic builds and we'll see how each client handles it.