I’ve seen threads asking about advice for keyed flutes, but I figured it’d be nice to have a survey of who uses what.
For me, 0. But I’m thinking of getting a 6 keyed flute soon-ish.
If you can afford it, get 8 keys.
I play traditional Irish, but I also like to play other types of music. The only key I don’t really use is short F, I pretty much use every other key about every time I play.
I have four (Eb, short F, G# and Bb… all for my right hand!) plus a C-nat thumbhole and use them all all the time. But didn’t get low C and C# because I found the traditional articulated keys awkwardly placed with the foot rotated to set the Eb where I like it, so would personally prefer Boehm-style keys for these notes.
No keys here, but I’m early in the learning process. I bought a very nice keyless flute a few years ago (a Forbes and Yolanda Christie “Windward”), and decided I wouldn’t invest in a keyed flute until I could actually play a decent number of session tunes at speed. That number varies, depending on how much I’m lusting after a keyed flute. 
I had a decent repertoire of Irish trad tunes on the mandolin before I started learning flute, and I can play almost everything I’m interested in. But there are still a few favorites that are difficult to reach with half-holing. I’m getting better now at half-holing G# and F nats, so that list is steadily decreasing, but I wish I could just hit a key for those notes. And there are one or two tunes with an Eb that I play on mandolin, and that just isn’t going to happen on this flute.
My problem now is that I’m totally spoiled with a keyless flute at this level of quality and power, and a keyed one at the same level won’t be inexpensive (sigh).
If you do a simple search you will find tons of posts related to the topic. My advice is if you can afford it, get a 6 or 8 keyed flute. They are capable of all you need them to do and in the event you ever want to sell the flute it will be easier to do so. You also won’t have the regret of wishing you had more keys later on. If you’re sticking to ITM 6 keys is all you really need, if you want to branch out then go for 8. Having foot keys for the novelty of the low C and C# isn’t worth the expense unless you plan on using them.
I’m not so much asking for advice on what to get as wondering what other people play. I know there are flutes out there with 10+ keys, and of course the Radcliffe and Boehm style flutes, so I’m curious who’s got what and whether they take full advantage of the silver they have.
6 on the instrument and 6 regularly played; I play a lot of French and Scandinavian music, so key signatures like Gm are a constant presence and the leys really come into their own.
I probably use the C nat key least because of the available half-holing and cross-fingering alternative options, but I wouldn’t like to lose any of them.
There’s a hat-full on my blackwood flute, never even counted them 'till now (there’s eight) let alone learnt what most of them do … the only one I use regularly is the low Eb (D#?) as a couple of tunes I play inlude it. I’d like to use the low C, specifically for “She Walks through the Fair” (though there are probably others), but I can’t get my RH little finger to operate the keys without one or more of the higher holes leaking. I’m considering extensions for those keys 
8 keys, and using all of them.
8 keys …so far ! 
The only key I’ve never used on my Monzani is the right hand Bb touch.
Can anybody give an example of when it would be useful?
Obviously Old Teobaldo wasn’t thinking of pipers grip too hand players so what type of passage was it invented for?
I have 8 and I use them all, exclusively for ITM. I don’t know which one I use least, but probably the Eb. I don’t get the people who say you don’t need the low ones for ITM… you don’t need any of them to play good traditional music, but my experience has been that the low ones are as useful as the rest (more than some)
When you need a Bb and chose to have one (like me) instead of the left-hand type! 
Have 6, use 6. But of course, a significant swath of my repertoire doesn’t need any.
As for “Tintin”, above.
I have eight and use eight. Playing ITM only with a few strolls to scandinavian music.
All those fiddle tunes…
My Irish workhorse is a six key Serov modern Large Hole Rudall copy. I have a Douglas (dealer) antique with eight keys I use for Jazz and other genre.
Bob
I just sold my 8 key flute, but of those 8 I really only used 7 of them (just didn’t use the Cnat very often…as in almost never). The low notes were less commonly used, but there were a few tunes in which they were handy.
Now I’m happy with a 5 key (all the usual suspects minus the Cnat).
Eric
To answer my own question it appears Monzani invented the right hand Bb for trills on A and Bb and other situations (according to Rick Wilsons site).
Though I still wonder what other situations.
I have tried to find a context to use it in but haven’t yet being used to the thumb Bb.
And Peter your thumb is employed elsewhere if I recall (cnat thumb hole) so right hand Bb makes sense for you
It’s certainly effective for that.
I have tried to find a context to use it in but haven’t yet being used to the thumb Bb.
Think what you’re used to is key (no pun) here. I’m used to RH Bb, so can’t see why you’d want LH. Just like I’m used to short F and couldn’t use long F, whereas others swear by long F and even build flutes without the short one. And I can’t now see why my RH G#'s not standard despite struggling with the concept for long enough when we were planning my flute!
And Peter your thumb is employed elsewhere if I recall (cnat thumb hole) so right hand Bb makes sense for you
Yes, that’s true, though both choices ultimately came through my desire for a simply elegant nine-fingered layout that wasn’t hampered by duplicate keys and long rods/levers (aka ‘scaffolding’) everywhere. And what I’ve got’s a brilliant solution for me (effectively a five-keyed flute with just four keys), though I probably play OXXOOO and OXOXXX (especially the latter when I want to cut it) more than thumb hole C and use the thumb hole for venting C# as much as anything else.