Howard,
Glad to hear that you at least do not dismiss my sayings theoretically:-) Now, do keep in mind that I am not trying to urge you into a transition from your habitual playing - only delicately(?) suggesting that IF you one day might experience the 'new world' of an improved 'handle' you might also see the point in recommending next generation(s) to adopt possible means to make learning and performance much easier, precise and comfortable.

H:" All I am saying is that in more than 30 years of playing I've never felt that the hand straps on my instruments were a problem, when properly adjusted. None of the points you list as "defects" are problems to me".

RE: I fully understand this position as being self-evident.You may be entirely satisfied with your own enjoyment from playing and thus feel no inspiration whatsoever to encounter novelties.BUT...I guess you do learn a new tune now and then, maybe you even wonder IF you might play something a little but more complicated than you are used to or
enjoy playing standing without the aid of stabilizing the instrument on your knee if you are mostly playing seated?

H:"I agree that stability can be an issue, but I don't rely on the straps alone for this - I usually support one end of the instrument. I'm not convinced that what you are proposing is the answer, because if the hand is to be allowed sufficient freedom of movement then stability is going to be compromised".

RE:Like I presupposed - do you support the one end on your knee while playing seated mostly? Ever playing standing? What you then say is one of the clues regarding the *concertina concept* as such: The need to compromise between stability and flexibility. Ideally we should use a "flying hand" for all keyboard work but concertinas do not admit that.Since tonal control (all articulation) is depending on stability the demands of musical quality inevitably mean that creating stability is a prime object.It ought to be more important to
play few but nice notes than reaching a multifold of notes but not being able to articulate them nicely...IF you have to make that choice

H:"I would be curious to try out an instrument with the modifications you're suggesting. However, as I said in my previous post, it seems to be a solution to problems I don't find myself facing".

RE:I would much enjoy offering you that opportunity one day...there are not only "problems" to solve here but offering means for expansion of ones capacity of musical expression and that may turn out being the greates benefit

H: "As for the air button, it is only dysfunctional in terms of the end joint of the thumb. The thumb is perfectly capable of sideways movement from the first joint. Since I'm using the thumb to exert pressure to control tension in the strap, it's more natural for me to use sideways pressure on the air button rather than a downward lever, although I can see that with thumbstraps you would have to use a lever".

RE: I said this before, but anyhow you are right of course regarding the thumb's movement capacities but additionally we have to consider the muscular effort which certainly may be negligable some times and then no problem exists but also may be considerable, depending on particular music, and then the static effort inevitably obstructs the free movements by the other fingers. Consquently the safest way to prevent such drawbacks is stabilizing the proximal joint of the thumb and using the distal part by flexing for a lever instead of a press button.

H:"(PS Henrik's instrument, when I last saw it and as illustrated on his website, has both thumb and handstraps - on an English. As you say, this is in part because he plays Irish music and wants to make more use of the bellows)"

RE:Correct, but since then he has dismissed the thumb strap since ( he has declared this also publicly) his pain from injured thumbs makes him prefer having thumbs loose. As a quack I both see his point and also question the solution but in the end his own practise ought to decide what is most comfortable for him personally.There IS a risk that additional working load on the thumb joint(s) may cause unheatlh
and this is one reason that I do NOT recommend using ONLY a thumbstrap.My suggested "uniform ergonomic handle" is primarily based on a broad slanting "wrist support" COMBINED with a broad anatomically adjusted wrist strap that by cooperation form a cuff for the wrist/hand that takes the major part of both stabilisation and guidance of the sliding which is necessary - just like you mention - to admit access to the distant buttons.With that arrangement I find a
fairly ideal compromise between stability and flexibility where the thumb strap basically is just the said pivot and thumb stabilizer while the major stability comes from the wristsupport/wriststrap system. This has to be experienced to be fully understood I think but it works entirely different from traditional 'handles'.
One additional point is that this handle arrangment easily can be used "normally" without any other re-arrangements than leaving the thumb strap or wrist strap out temporarily and taking the wrist support away when maximal flexibility for some reason is needed.