I cant say if this is related to an improovement or not...
I only can state that older tracks that make use of extrem shiftings sound different.
More hf content and different behaviour when fine shifting the startmarker.
I wouldnt say that the basic quality of the algorythm has changed..its the same crunchy stretching but sounds slightly different.
If there are no real resons or benefit in that ( like better timing or so )
i would prefer my old mixes to sound the same