This hash sounds right up my street! I love the clear high from the Durban and you're lucky to get it in hash form.
In answer to your question, full melt sometimes referred to as full melt clear dome is almost completely made up of trichomes with little to no plant matter. When it's ignited it bubbles/melts indicating the very high quality. The more plant matter the less pure the hash is deemed to be.
Personally I like hash like the one you're smoking now with some plant matter in as the strength is manageable, it's easy to smoke and I find the flavour more complex. Strictly speaking it's lower quality but beer is also lower quality than vodka by the same logic and I know which I prefer!
Aslong as the hash is good quality and not bulked with filler or actual fake hash with research chemicals added (yes that's a thing), then as far as I'm concerned it's good hash. A little plant matter doesn't bother me and actually helps it burn better in a joint and is easier to handle imo.
If I was offered the same hash and could have 7g of full melt or 28g of mid grade hash from the same inputs I'd take the latter everytime. I know that's not the popular opinion but it's my personal preference.