This is from Harrison's book.
A bow strung with a continuous-loop bowstring shot the same arrow an average of eight to ten feet per second faster than a bow strung with a Flemish-twist bowstring. I also noted there was more hand shock and vibration with a Flemish-twist bowstring.
Obviously his tests were skewed. If you know what you are doing, you can make an endless that is faster, or a flemish that is faster. Both strings equally well made will show little to no performance differences. There have been flight records set with flemish strings.
Besides the inaccuracies, he threw in what could very well be considered an insult to anyone who likes flemish.
Finally, as a point of trivial history, it became vogue to shoot Flemsish-twist bowstrings as a desperate attempt for some over-zealous apologists to return to "tradition" when compound bows came into being.
If you prefer flemish it's because you are an "over-zealous apologist" making a "desparate attempt"?
Although I have shot endless, and may still shoot one from time to time, I always preferred flemish because they are (for me) quieter and easier to adjust for fine tuning. I've never been one to worry about what is considered "vogue"...
Again though, that was Harrison. No idea what Mr. Fisk's thoughts are on the subject.
Back to the O.P. Other than voiding the warranty, the rest is simply not true. You can affect performance much more with your release than you will see between an equally well made endless vs. flemish.
I suggest that anyone wondering compare for themselves.
Chad