Joe Kissell, Mac guru and author of the recent downloadable book, Backing Up Your Mac (https://www.takecontrolbooks.com/jot-backing-up), has mentioned QRecall in his backup books and articles since 2007:
https://tidbits.com/article/9270.
QRecall is also listed on his website list of backup software:
https://joeontech.net/extras/buym/