I have two computers (both Macbook Pros, 2.7GHz, 16GB, quad processor). One is 2012 vintage and the other is 2016 vintage. The newer one has a very fast SSD, the older one has an SSD that is significantly slower but still pretty good. On both machines I am streaming from the internal SSD.
I have a midi file that stresses the SSD pretty hard (over 400-500 voices in some parts depending on the mic preset). The older machine has problems in the more stressful parts of the playback. The newer machine has no problem ever with this file. When looking at ther CPU monitor, the older machine hits 100% in several places and it is here that I hear samples cutting out. The newer machine never gets over 75% even with the lowest preload setting. The old machine hits 100% often even with the highest preload settings. But the preload setting does make a difference.
The SSD speed is the only significant difference between these machines. I suspect the SSD speed is why some people are having problems and others aren't.
Anyway, the logic pro project and midi file are at the link below so you can test on your machines and monitor the CPU to see if it gets to 100%. I think that is when the samples are cutting out.
https://www.icloud.com/#iclouddrive/0cns36_RgsPKidH8NUCcurESA