My new personal sling philosophy is that the slinger is what matters. A slinger should train with all kinds of sling he can think of or utilize from this direct environment. Cotton strap slings, leather belt slings, heavy slings, long slings, short slings, captive slings, stiff slings, floppy slings, braided, twisted, small pouch, large pouch, light, heavy, medium stones of all sizes and shapes, staff slings, direct throwing styles, rotor styles, at any release angle, with wide grip, tight grip, wrist loop, finger loop, no loop, smooth release cord, knot release, big knot release, tab release, loop release. All of this gives the greatest adaptability. I think adaptability to slings is key. A good slinger can get around with even a belt as a sling because he will know how best utilize it. For example when I use my canvas belt as a sling I know it needs ~400g rocks to shine and a direct-no rotor throwing action.
This adaptability allows the slinger get a sling from materials the environment dictates and use it in a manner which the environment allows. As long as it is flexible enough it can be made into a sling and I feel like I can adapt to any sling setup now with an ~hour of training and get proficient enough with it. With ammo, aim for natural stones of various shapes and sizes as this is the most available. And train at all distances...

You could stamp in a certain specific slinging ritual with a certain specific sling or only a certain weight of stone and get really good with that specific sling but
what if you lose it...or what if there are no such specific stones you seek, or the environment prohibits the use of your slinging style that you have solely practiced?

We can place a static target where our sling projectile goes and hit it consistently, and think we are a good slinger, but fool ourselves.
I think what determines a good slinger now is the ability to adapt.
When you train with such varying slings and styles you just notice you get the ability to swap between slings very quickly.
And the training I do with one type does overflows to the other. Because good form is key to all styles.

I'd beg to differ, based on much observation of Balearic slings in operation in the Balearic Islands.
Half the slingers struggle to throw the right size and shape rock without the damn things coming out sideways or backwards.

Simply by having a great big hole in the middle, a split pouch will always be more limited than a solid pouch.

If it works for you, great
But believe me, they are a long long way from being the perfect sling design.
Watching Balearic slingers proves that in spades.

They are specifically designed for big rocks at short ranges, and then only because it's a fairly easy and quick design to make with very basic materials that grow wild on the islands.

Pretty impressive watching someone pick s handful of grass and have s completed sling a couple hours later.
But they are very much horses for courses.

Curious Aardvark wrote on Sep 27^th, 2021 at 7:45am:

The point of a split pouch is to be able to adjust the size of the pouch to the size of the projectile, and because the flat braids sit underneath the projectile, it's not physically possible for the projectile fall through, unless you are trying to lob greasy, mirror-polished tungsten spheres.
I don't see Luis or Jaegoor having any issues with 'Balearic' slings, and I haven't encountered any myself, so you are incorrectly assigning the problem to the design instead of the user. I have seen the same issue myself when teaching my brother how to sling, where the stone flies out of the pouch unintentionally, but I never have any issues at all when using the same sling. It is due to the sling being rotated incorrectly, not the sling itself. Give the same balearic slingers who where having stone retention problems a cortaillod sling, and they probably wouldn't be able to use it at all, my brother certainly can't, even though the cortaillod is what I would consider 'peak' sling technology, and works terrifically in the right hands.

Whenever I am in a place with stones I am glad to have any kind of sling with me. There were times I had to resort to using my canvas belt (rip.) but anyway that's hours of fun right there

   Here's my two cents.  There are many excellent designs and materials to chose from.  It comes down to personal preference.  The sling I'm most comfortable with is a modified pj with an elongated pouch.  Jute is my material of choice.  It certainly won't last as long as a sling made from synthetic fibers but I like the feel of it.  Honorable mention goes to the TS3 and Rockman.

I like a versatile sling design that can work with a wide variety of rocks up to 500 grams in weight.
That requirement doesn't require an extraordinary special design.
Leather seems to be able to handle the most abuse.
A higher rock weight can make up for many imperfections. Little fast flying stones however have to have a good
round shape if they want to be anything for me other than useless

And yes I know the colors don’t match, but this sling works very well for the first design.

Ich slinge nun schon wirklich lange. Und immer wieder kommt die Frage nach dem besten Design. Dem besten Stil. Steine bis 500 g.  warum? Kann man machen. Für Anfänger ein No Go. Welches Material. Usw. Sie wollen gut werden? Wählen sie ein Design. Einen Stil. Trainieren sie Konsequent. Ganz einfach.