Well, this went a lot better than expected, so I'll skip another disclaimer and just refer to the first.
Let me just throw around a few thoughts and comments.
If anyone can make a smoothly moving joint that will stay put and stay that way indefinitely then patent it and sell it to doll makers.
Arguably Doll Sweet / EX Doll / Arte Tokio did ...
One can differ about whether they succeeded for 95%, 98%, 99% or. 99.9% - but the normal perpendicular rotating joins( as opposed to axial) in their skeletons run smoothly without loosing much( say 10%/year) strength over time.
However, unfortunately that is still not the holy grail or a magic bullet as someone called it earlier.
From the experiences of two tpe dolls the joints have all been very very tight to enable them to hold a standing pose.
For play this is detrimental to the pleasure of tpe dolls as you expend so much time and energy altering their limbs as there so very tight .
As it is currently done, joints hold their state by friction.
From a physicists point of view there are at least two important states here, the one while everything is stable, held in place by the friction and the one where stuff is gliding smoothly against some resistance.
I will not bother looking up the exact terms for these, but it should be easily clear that the friction holding the stuff in place is higher than the gliding one so you always need sufficiently more force to leave the stable state and initiate gliding than you need to just maintain the glide.( If you reverse it, consider the more power you apply to a brake the less it will glide and eventually it will stop and be held.)
Now, with respect to the quote - for play you want smooth movement( without the initial higher effort) and little resistance - for a standing doll you want high resistance and do not care about the effort to move between positions.
So, in effect - unless the basics change - this is an either/or design choice.
If - hypothetically speaking - the joint design and locking mechanism would be different, say ball bearing joints with electromagnetic brakes you could get the best of both combined - but with current technology( even such interesting things as electrically actuated muscles) the price tag for such a doll would make current high end dolls look like cheapo special offers.
Hmm, while I am at "high end dolls", some thoughts on that.
Everyone is entitled to their abstraction of what the term means, but I think it does not normally refer to "all the features there are" but more to either a simple monetary evaluation or the related but not equivalent "perceived value".
As for the standing ability in the high end dolls, I would have thought, given at least my impression that these dolls were primarily used for photography that there would have been a demand for standing ability for them even before it became popular with the less expensive dolls like Sanhui, or Z-Onedoll or even DS before 2014, I also am surprised that a doll had that ability and then lost it and there has apparently not been enough call for its return to prompt DS to re-offer it.
None of the ones mentioned here are "high-end" dolls from a monetary point of view, those would be say Real Doll, 4woods or Orient Industry dolls to name a few, each being several times as expensive as either the low-end( Z-Onedoll) or mid-range( Doll Sweet) of silicone dolls( who admittedly may all be viewed as expensive from a TPE point of view).
The other high-end perception relates to the value seen in the creation and features such as lots of options to choose from to personalize your doll, very refined body sculpts or particular beautiful appearance play a major role( see "Quality" below).
It is also no way a given that a doll being made from silicone automatically implies more photographic use - even the opposite is not entirely so, that is not all dolls look good in photos just because they're made in silicone - but I would still state that on an average level the sophistication or attention to detail is somewhat higher with silicone dolls.
Even if I reiterate it a bit here, maybe with different words or examples, there is no real relation of "standing ability" and "high-end" or "perceived value".
Consider the two options I already mentioned being an either/or choice today and lets call them "Sex Doll" and "Companion" for a moment, then add a third category based on realism and call it "Artwork" and another one called "Quality".
You can now go and choose how many points( read $) you want to spend on these topics and will then find the company or doll that suits you best( in a sense how many points/$ you are willing to spend is your final choice).
To illustrate this from my point of view, if I am willing to spend a lot of points on Companion, Quality and Artwork I may end up with Orient Industry, if I am willing to spend quite some but not as much on a Sex Doll and Quality I may go for a Maidlee Doll and if I am on a budget and looking for Artwork I might get a JM - all this for illustration strictly from the choices above and completely ignoring the fact that the company recommended may not even produce a doll you actually like.
This was meant to say - the companies out there know very well what they want to produce - well, usually - I am not so sure about Doll Sweet and the standing issue.
So - on the other hand - all you have to do is evaluate what you like and then get that.
Imho "High-End" means you get some more of the aggregate of the categories then with "mid-range" or "budget", but that's about it.
And if - apart from all the theory above - you can actually find something that really clicks with you, well, all the better.
Oh, and Ray and Incred et al. - I love your pictures and they would not benefit artistically from leaving the evidence within, in fact part of your skill to admire is to make the support vanish, my comment was meant for threads like this one specifically - though it probably wont hurt no leave a note nearby "used support gear photoshopped out" or the like.
Well, so much for this round.
All the best.