Well, to keep us out of an argument, I will say I can only agree that the Upanishads and the Gita speak on Rebirth, which is an aspect but distinct from ancient concepts of reincarnation that still persist.
My whole thesis is that the religions of God teach transcendentalism and physical rebirth has nothing to do with transcendental nature. Also, no one is omniscient as Lord Krishna or any Divine Manifestation of God, otherwise there would be no need for Them, and anyone could make the claim of being equal to a god. In fact, the word siddhi DOES NOT equate or mean in any sense of the word omniscience, but denotes a special capability developed, and means "perfection", "accomplishment", "attainment", "success"; see siddhas, which represents the "upright ones" who have disciplined themselves in cultivating spiritual insight and powers.
To clarify again the dimensions distinguishing Atman from Vijnana, it is important to re-read my post in how I described it. In respect to the dimensions of the ego there is what we psychologically describe as the superego or ID that at times with discipline can manifest as superconsciousness/hyperconsciousness, which is the Soul-Mind the Buddha described. Atman is essentially the same but the word itself meaning "self" can also have limited aspects of the skandhas to it that the Buddha wished to do away with immediately. Keep in mind that the Buddha expanded Vedic concepts and language to whole new dimensions.
Relating back to the siddhi complex, my understanding is that this prowess allows recognition of past rebirths, which today in modern psychology (influenced by Vedic-Buddhist philosophies) has described as the phases of psyche every human being naturally undergoes, from infancy to childhood, to adolescence and adulthood, to seniority and death stages; also related in the Bible as the 7 year cycle (of 12). Again, the importance is on the Mind (Citta), being the essence of the rational soul and not the body. A deeper question to consider is thus: Could not Brahmanic interpretation of scripture, in fact, be skewed, as Mahavira and the Buddha came to refresh and give birth to a new Dharma that has evolved?
Dear, brother Satsangi, upon investigating the etymon of Satsang I come to find its root cognitive for an essence or issuance ("Sons of Brahma") as manasputras ("born from the mind") of Brahma. Again--the MIND is the prime feature of reality and consciousness! This is my focus, and not the body, but the mind-body. In my humble opinion this is what the Divine Educators were focused upon and nothing more or less. Satsang also means "eternal" or "Eternal Dharma", and again, when we focus upon the dimensions of the Mind-Soul we realize that only through this evolutive process can we find liberation and salvation.
My most logical explanation for the Rishis is that one aspect is that they are a coded symbol for the Stars of the 7 Eons (7 Rishis) that were known to the priest-astronomers who would have been the seer sages recording the Vedas, so their states of higher-consciousness were dealing with abstract thought where we derive our sciences and philosopies today. As I've posited in other threads, I believe, along with other Baha'i comparitive religion scholars, that according to the historic composition of the Vedas (1000 BC) that their inspiration comes from previous Avatars (Manifestations of God) in history at some point and that their tradition stems from a continuous lineage--and Krishna testifies to this when He describes previous Teachers (such as Rama or Vishnu) and says that the Dharma is eternal and unchanging. To be fair, it must be observed that the appearence of the Rishis and the Rig-Vedas date to the exact time of the Advent of Krishna (approximately 1200 BC), though most are not truly certain as to His historic appearence. We base our knowledge from comparing the acknowledged timeline of the Vedas with discoveries in the Giza Pyramids, which we believe to actually be a "book in stone" in fact mentioned in the OT Bible and chronologically narrates the advent of every Messenger of God with accuracy.
Peace and Blessings from the Most High