The contradiction between sutra and tantra on the one hand, and Dzogchen on the other, concerning the difference/non-difference between mind and matter is not an important contradiction.
This is an intriguing point that Malcolm has made a few times lately. I had never heard it put in quite that way. I'm wondering, Malcolm, if you could give a short explanation of the sutra, tantra and dzogchen view on mind/matter. I would have thought that even in sutra, and definitely in tantra, because the nature of both mind and matter is emptiness, there would be no such dichotomy.
If you elevate everything to the ultimate level, even "...matter is unconditioned without anything missing", as it says in the Yum Chenmo, the sutra of Perfect Wisdom in 100,000 lines.
But the Buddhist scholastics from Sarvastivada up to Dharmakirti have always maintained a hard division between mind and matter, between nāma on the one hand and rūpa on the other. For example, in the account of the twelve links in the Vibhanga, the Pali Abhidharma compendium, when discussing the twelve nidanas, it even leaves off the rūpa in the nidana of nāmarūpa, running ignorance, formations, consciousness, name, etc.
The Yogacara school attempts to supercede this dualism through asserting that everything is fundamentally a projection of the mind -- in fact the 15th century Lamdre Master Khyentse Wangchuk states, there is no dualism of mind and matter because everything is mind.
As we know, Madhyamaka adopts the conventional truth either according to the Sautrantika system, or the Yogacara system. But since it's own perspective is grounded in the Prajñāpāramitasūtras, it regards distinctions such as mind and matter to be merely conventional designations that do have any real basis apart from imputation.
But we can see that this division is well preserved in Buddhist tantric literature (as well as Hindu tantric literature) when we find for example that the mind is described as a rider of a horse, vāyu. This is because both forms of tantra, Buddhist as well as Hindu, are concerned with the mechanics of the body for understanding how to gain realization through our embodiment through the practice of various kinds of yoga.
Granted, this is sometimes is found in Dzogchen literature as well. But when we examine that actual system of Dzogchen according to the ancient Dzogchen tantras, we find that in fact even consciousness itself is generated phsyiologically in the body by a vāyu. I have yet to find in an original Dzogchen tantra the common Buddhist term khams drug, sadadhātu i.e. earth, water, fire, air, space and consciousness. I may yet find it, but at least the Valby KWIC tool does not in fact list it in the 83 or so important Dzogchen tantras that he converted into searchable text files. It also does not list every instance of thod rgal in the Dzogchen tantras as well so its look up routines are not completely infallible. But there are hundreds of references to the five elements ('byung lnga, pañcabhutani).
I have been also examining the Mdzod phug lately, Bon "Abhidharma" and cosmology, is largely freed from the constraints of Buddhist conservatism, has very interesting things to say about the five elements and so on, and when is a text clearly influenced by Dzogchen. A kind of Dzogchen Abhidharma. One of the reasons why I started looking into this text is that the Rigpa Rangshar tantra contains a very breif mention of a primordial egg cosmology which accounts for the formation of the world, similar to the Vedas and Bon:Now, to demonstrate the ignorance of the object of delusion: delusion is deluded by the forgoing. The field is prior to the formation of the world; a so called “wish-fulfilling tree” grows, a tree growing from the blessing of the youthful vase body of the buddha, born from warmth and moisture which arose from an egg. The Sahāloka formed from the mind disturbing the so-called self-originated wisdom in that. That is called the ignorance of the field of delusion.