Do you at least understand now what I mean?
If you mean what I said, yes.
Crans take practice.
Speaking only in terms of flute and whistle, the use of cranns for me has become an aesthetic matter rather than a mere convenience to stand in for a roll. Once I learned how to do them, I was delighted and threw in cranns at every opportunity where it fit well enough. I’ve grown away from that. I still use them, but if that’s all I do at the expense of other more melodic alternatives also available to me, it’s a bit of an old-dog-no-new-tricks thing; rather one-dimensional.
Assuming the timing issue has been conquered, making a crann sound crisp - or at least not flabby or muddy - on whistle and I think especially flute is the big challenge. With pipes you don’t get that problem if your reed and fingering are sound. If I had neither the timing nor some semblance of a crisp-sounding delivery in my cranns, I’d probably avoid them altogether in public playing, and just keep practicing them in private until I got them down.
In my experience it’s phrasing that takes practice.
Well, I’ve been trying to wrap my head
around that one, actually. I submit (and
correct me if I’m wrong) that a cran is
merely a roll with a second cut in place
of the tap. If the second cut is in the
same position in time as the roll’s tap,
won’t the phrasing be exactly the same;
the third note starts at the same place
as it would with a roll, right? Seems to
me like the phrasing should be equivalent.
What am I missing?
I think it’s not a bad idea to clarify some things, first. Especially as relates to the pipes, there are so-called “true cranns” and “false cranns”. You basic true crann (and there are variants) goes thusly: (A) D (G)(D)(F#) D. A false crann is easier to work, as it tends to go something like D (G)(F#) D (short blippy notes in parentheses). Doing a true crann well on whistle or flute is not an impossibility, but the phrasing challenges will indeed be greater for it. A so-called “false” crann will often sound just fine to my ear on flute or whistle, but it’s still discernibly not the “official” thing. Again, that’s not a negative, because what sounds good is what’s more important, I think. I use both, myself.
I use both, but I’m following Grey, who taught me to do a D cran this way.
D, cut E, cut Fsharp, cut E, D. E crans are the same, but a note higher. If I understand you right,
that’s a true cran,
at least its in the same time as your true cran. I think. Almost. I had originally done ‘true’ crans
roughly on the piping pattern you give above–but without the preceding cut A. Grey says that the way he advises works
better in the second octave, which does seem right. The notes are less likely
to break.
These take a lot of slow practice, but, well, what doesn’t? Finally they come
in handy. I think there’s a tune, The Unknown Reel, where I discovered that
I preferred them to rolls.
It falls roughly within the parameters that pipering calls a crann of the “true” sort. But number and order of notes alone doesn’t tell us how a thing is phrased. As I mentioned, there are variations - sometimes a crann is played with a reversed phrasing, for example, or is done with a reversed cut note order, or uses cut notes different from the basic form - but the method of using the E so is rather foreign to the usual piper’s way when it comes to cranns. Certainly for me the E cut is very awkward in this instance, so I wouldn’t even think to use it. But, successful phrasing and timing are what count in the end.
The preceding A cut is part of the package of the classic crann. Without it, you have a variant. With pipes there is a further purpose beyond ornamentation in the preceding A cut, for it is a technique that is more likely to ensure a hard bottom D on the chanter. For flutes and whistles, this becomes of course more negotiable.
I suggest that that breaking is all a matter of the player’s control and embouchure.
I believe that as with all things, ideally one should be able to do a classic crann before one does alternatives. Not least is the basic phrasing, which is like “ba-DUM, diddle-UM”. An example of a reversed phrasing would be “ba-DIDDLE um, DUM”. Mick O’Brien went with this particular variant on the last jig in track 1 on his CD May Morning Dew.
I think the issue is that there is no phrasing for a roll or a cran (or at least there shouldn’t be). Rather the roll or cran relates to the phrasing of the tune. The big issue in my mind is that the roll or cran will span the transition from one phrase to the next. Which means (in a reel) that the last note of the roll or cran must be played so as to sound as the pickup for the next note, rather than as the afterthought of the preceding notes. In a jig, when this happens, you will want the second and third note of the roll or cran to sound as the beginning of the next phrase rather than end of the last. Mind you I am thoroughly out of my depth here as I am just learning this: it is taking me a lot of listening and playing to hear the phrases and microphrases in tunes and to learn to reproduce them. So much in fact, that by the time I’ll understand the phrasing of tunes, putting two or three cuts into a dotted quarter note will be trivial (it already is, actually). To be blunt: twiddling your fingers on D or E while butchering the structure of the tune sounds like shyte, not matter how crisp the cuts.
I find myself both disagreeing (per my above post on cranns) and agreeing with you (if you’ve been reading the Book of Five Rings). 
I agree that you’ve got to know what you’re doing, and why. On the extreme end of this, I know a fellow who was told by an old-hand whistleplayer on the subject of ornamentation, “Ah, I just waggle me fingers,” and the fellow literally took it to heart for his own playing. The result was not attractive.
There are a stack of tunes - the Floating Crowbar, for one - in which texture variations on the recurring low Ds is what makes the tune. You can’t play that well on a whistle without cranning.
So I think like everything in music it’s a matter of degrees and shades. Certainly there are some tunes that it is easier to put crans into and preserve the phrasing than it is in others. If you want to put crans in your whistle playing (which I don’t recommend, mind you), there are some tunes you’d want to start with, true. Like Fraher’s or the Blarney Pilgrim. I’ve stopped putting crans in either after listening to myself, though, to everybody’s relief.
As for the Floating Crowbar that you mentioned, I think it’s better off on whistle or flute without the crans. Certainly it’s not a requirement to have them in there, as this recording shows, which has no crans: http://www.box.net/shared/ed4gmf4lrt (that’s not me playing, but a friend).