What information does the preface provide about lesser-known or alternative Guru biographies besides the most famous ones?

The preface discussed in Chapter 0 mentions several Guru biographies that are not as widely known. It identifies a 'Laghu Guru Charitra' from Wadi, a separate and much older work than Saraswati Gangadhar's, containing only 707 verses. It also refers to a detailed and scholarly biography written by Shri Samarth Sadguru Tembhe Swami, also known as Vasudevanand Saraswati Maharaj, which did not become as famous as Saraswati Gangadhar's work. Lastly, as Chapter 0 notes, there is mention of a Guru biography by Shri Samarth Sadguru Dattatreya Maharaj of Balekundri, which was believed to be unprinted and unpublished at the time.