I use both fingerings for F#, but I fail to see the advantage of one over the other for Irish. For me, fingering is kinetic, and I want to use my forefinger to play F#, not my middle or ring fingers. As a result, I am not comfortable using my Boehm flute for Irish. If I wanted to make the transitiion, I would pick one or the other, but I’m not willing to get dextrous enough to do both.
Just my $0.02:
- I have no problem rolling F#s, but I’m not sure if I use what James posted. I guess I need to check.
- But you CAN roll Cnat/# using the trill keys. And that is both cool and also useful. It’s an non-standard roll sound, but it’s there :=)
- I have an open hole Böhm flute and, having tried a closed hole flute with simple-system tunes have to admit that open hole feels much more like a simple system flute.
And, to quote:
The mistake some other folks make is assuming that what you can play well on one can’t be played well on the other: it can, though each requires a somewhat different approach.
Absolutely:
- Bach on my Reviol is fun to play (and sounds quite nice too)
- And there’s no way I’m learning Paddy McFahy/Julia Delaney/The Girl I Left Behind Me on my D flutes
D minor tunes are just GREAT on 8-key! Get that long F and the upper C key going as well as the foot keys!
Sounds good. Thanks. Like I said it was in response to a problem that was already there, so I wasn’t sure if it woulda been smart to do it by itself. Thanks for clearing that up!
Just a further note on those adjustable linkages:
If your flute has soft pads in oversized keys (like many of the more inexpensive flutes), then if you get those adjustment screws pretty close, the flute will play. The soft felt in the pads gives you some “wiggle room.”
However… (you knew that “however” was coming, didn’t ya? 
)
If you have a flute with pads that have harder felt, like those found on higher-end flutes, those adjustments are very delicate and making those adjustments (which is called “regulating” a flute) is very delicate and can be lengthy, frustrating work even for an experienced hand. If you move those adjustments on one of these flutes, there is basically no chance that you’ll be able to get the mechanism back into adjustment by yourself.
So use real caution with those adjustable linkages!
–James
P.S. If you think regulating a flute can be hairy, try an oboe!!! 