So, how do you go about when cutting D’?
I use the oxx xxx fingering, because that’s what I learned to do from Bill Ochs book.
But, when cutting I get a considerably “lower-sounding” blip than other cuts, probably because the cut is made with Cnat. oxxoxx
Use the xxx xxx fingering. Cut with T3 or B1 or B2 (I favor B1).
Thought of that too, alas I think xxx xxx doesn’t sound as good as oxx xxx.
The transition between octaves seem smoother with the latter.
Maybe I should continue to use oxx xxx, and when I know I’m gonna cut I’ll just play a D’ pre-emptively with all holes covered… maybe that’s what most people do?
I learned OXXXXX for the second octave D and to cut all my D’s with the T-3 finger ( XXOXXX and OXOXXX). Sounds fine to me.
Right. There’s nothing sacred about the oxx xxx fingering. Try this: play xxx xxx, then quickly trill the T1 finger. On most whistles, there’s no audible difference. Sometimes oxx xxx speaks more easily when approaching it from a different note. So learn to use both fingerings, whichever one gives your fingering a smoother flow.
TMTOWTDI - There’s More Than One Way To Do It. 
If you must cut on oxx xxx, cut with B3 (oxx xxo). That works better for a mid-cut d{e}d than for an open, initial cut {e}d.
I usually avoid D/d cuts anyway. I find them to be awkward. They’re not needed for D rolls, because you cran the D. Instead, I usually substitute what I call the flip: {de}d, {dg}d, etc. - basically a single trill or mordent. It’s “punchier” on the lower D. And on the 2nd octave d it’s more stable and easier to finger, and can be used with either d fingering.
In general, you can almost always substitute a flip in place of a cut. Think of it as just a variant of the same ornament.
The problem is - as Rhadge said - you’re then cutting from below, which sounds quite different from a true cut from above. In the case of oxoxxx {=c}d, the c-(super)nat kind of slides up to the d, and is not nearly as crisp. In the case of xxoxxx, I don’t know any whistles on which that cut note is stable. You’re either cutting with 1st octave A (4th below), which gives a weird burble, or you’re venting the whistle to play 2nd octave a - where the whistle wants to “lock in” and stay there. Too many problems, IMO, when there are multiple better alternatives.
Informative as always MTGuru.
I find that the difference between xxx xxx and oxx xxx, is that the airflow is a bit more “pronounced” in the tube, with the former. It probably varies between whistles though.
Your way of cutting indeed gives it a more lower-sounding punch. But I’ll stick to lifting T3 though on the lower octave since I’ve gotten used to it, but it’ll probably be a nice addition in the future to my technique repertoire. TAMTOWTDI, was it? 
Regarding D’, flipping the note worked quite well. Thanks.
I rather like the sound of a cut D’ with the top hole vented. Micho Russell seemed to, as well
MTG, what is a “flip” - maybe what I describe below?
A nice thing you can do to accentuate a long D’ is a kind of rapid trill at the attack of the note: {c#dc#}d. I use T2 and T3 together to do this, which is easier than using the 3rd finger alone:
[| ooo-xxx]
[| oxx-xxx]
[| ooo-xxx]
[| oxx-xxx]
I find this a more punchy alternative to a cran for say, an accented dotted quarter-note/crotchet at the start of a reel. You can omit the first c# for a less fussy-sounding version.
That trill thing with T2 T3 is a nice trick.
Anyone has advice regarding performing a cut between a D’ and an E’?
I find that it does differ between whistles. On my new Overton tenor D, the XXX_XXX gives the clear and accurate note, while the oxx_xxx gives a slightly sharp note. I am relearning some tunes, as I was used to using the alternate, but I really like the fuller sound of the xxx_xxx. On other whistles, I still have to use the 0xx_xxx to get the clearer note.
I tend to use B1 or even B2 for the cut on the lower whistles, and T3 on the high.
NOTE: Any opinion expressed by me as to the authenticity or accurateness of a technique is strictly amateurish and untrustworthy.
Agreed, actually. I really just want the OP to be able to hear the difference between the two.
Nice. I forgot about that one.
It’s just my term of convenience for simply starting the cut on the target note. In other words, instead of e.g. {B}G you play {GB}G. It stands sort of in the same relationship to a simple cut as a condensed long roll stands to a short roll. So maybe “long cut” is a better label.
It happens naturally in descending cuts anyway, if you’re a tad lazy coming off of the cutting finger. That is, e.g., instead of B{c}A you get B{Ac}A. The tiny difference in timing gives you an “A flip”. And on its own at the start of a phrase {Ac}A it can add some nice definition. My friend Ben Power thinks it perhaps sounds more Northern or Scottish, and I do hear it quite a bit in the fiddling style of, say, Natalie MacMaster, Alasdair Fraser, etc.
Hmm, not on mine. The two are identical.
With d xxx xxx, just cut the e normally. With d oxx xxx there’s a lot of awkward finger movement on both hands. Cutting with B1 is probably easiest. But this is another situation to prefer d xxx xxx.
It’s probably me, but there is a noticeable difference. It requires more control and attention than I have been used to paying, but wow! What a gorgeous tone and volume when I get it right.