I've just read the following about "Tathagatagarbha":
"Both the Shurangama Sutra and the Lankavatara Sutra describe the tathagatagarbha ("arahant womb") as "by nature brightly shining and pure," and "originally pure," though "enveloped in the garments of the skandhas, dhatus and ayatanas and soiled with the dirt of attachment, hatred, delusion and false imagining." It is said to be "naturally pure," but it appears impure as it is stained by adventitious defilements. Thus the Lankavatara Sutra identifies the luminous mind of the Canon with the tathagatagarbha. (Some Gelug philosophers, in contrast to teachings in the Lankavatara Sutra, maintain that the "purity" of the tathagatagarbha is not because it is originally or fundamentally pure, but because mental flaws can be removed — that is, like anything else, they are not part of an individual's fundamental essence. These thinkers thus refuse to turn epistemological insight about emptiness and Buddha-nature into an essentialist metaphysics.)
The Shurangama Sutra and the Lankavatara Sutra also equate the tathagatagarbha (and alaya-vijnana) with nirvana, though this is concerned with the actual attainment of nirvana as opposed to nirvana as a timeless phenomenon." [?] -- Wikipedia
I also thought the "luminous all around" consciousness mentioned in MN 49 and DN 11 is the mind essence. However, after reading Ajahn Maha Boowa's description about the well cleansed mind (which is "luminous all around" with the subtle emptiness but not yet free from the delusion of the "knower") and the completely cleansed mind (the transcendent emptiness of the pure mind which has no radiance anymore and free from all delusion) in "The Path to Aranhantship" and "Mae Chee Kaew – Her Journey to Spiritual Awakening & Enlightenment" --http://www.forestdhammabooks.com/, I realized that the shining mind which has been believed to be "Tathagatagarbha" (as stated in the quote above) is not yet the pure mind. I'm very grateful to Ajahn Maha Boowa and Mae Chee Kaew for their great contribution.
I'm not familiar with Chan, but read a story which seem to also indicate that the radiant mind is not yet the mind essence:
The story is similar in essence to Mae Chee Kaew's practice from the radiant mind to the empty mind (as I understand), so I'm not going to translate it. If some Chinese friends know more about the radiant mind vs. the pure empty mind, I'd like to learn more.
Thought this is an important issue and would like to share/exchange info with the friends here. All the best,