split strut means the struts are not "under" the canopy fabric, but "in" it, connected to the canopy by 2 seams instead of one.
Split strut was most likely mainly left off some new models to save on sewing cost and development issues/time as SS branched out into more different types of kites.
One seam is cheaper than 2 and the split strut assembly needs more strips of cloth and more seams, plus a need for more different types of seams in the canopy, compared to conventional build.
Split Strut Pros:
-changes the feel of a kite
-can provide some absorption of gust as canopy tension deforms the strut (and v.v. as the tension decreases).
-also helps with durability
-geometry helps keep frame rigid and canopy tighter, so good for performance...(?)
There were other reasons for leaving it off too:
-saves a little weight
-cost and complexity
-probably also simpler/cheaper for the the rider to repair if it breaks
But they brought it back and that is probably good, since it helps support the kites' unique qualities and reputation for strength and durability.
Nothing wrong with the prior rpms and recent fuels without split strut though, they are all good kites imho.
a simplified visual explanation:
sorry for being late but i have some reservations.
first of all not 1 seam instead of 2, but 3 seams instead of 5. so, if (lets say) strut is 1,5m long you have to stitch 3m longer, not just 1,5m. just because strut is now made from 3 segments, not 2 as before, plus 2 seams to stitch canopy to each side of the strut.
then, there are practically no pros for splitstrut at all:
-bet if there were "blind" test of the split and regular struts there would be no noticeable difference in the "feel" of the kite
-there will be certainly some absorption by the strut in split-strut version but i'm sure it will be marginal compared with overall elasticity of the canopy material and flexibility of the inflatable LE bladder and the struts
-more seams (eg cloth perforation points) leads to less durability imo
-and as you stated earlier, "some absorption" (though almost negligible imo) can not contribute to the rigidity of the frame and the tightness of the canopy
plus there are now two 1 and 1/2'' wide dacron stripes per each strut instead of one on the traditional strut for connecting the teijin to the strut, so there is more added weight.
don't you think so?
so, for me it is just unnecessary waste of chinese workers time and money in form of materials and marketing costs.
the simplest solution is the better. no need to revive gone long time ago ineffective solutions, even if they were original.