I believe that the tekkit mechanic that you are referring to is the Equivalent Exchange 2 EMC mechanic (using the Transmutation table, Antimatter Relays, Condensers, etc.). Many view that mechanic as somewhat broken, primarily because it meant that you could basically replicate any item with an infinite cobblegen, or equivalent source of sustainable matter.
The Equivalent Exchange mod itself is currently in the prelease stages of an overhaul (Equivalent Exchange 3), and is the source of the Minium Stone item available in most packs (the precursor to the Philosopher's Stone of old), but I wouldn't be expecting any similar catch-all system to be implemented any time soon.
To the best of my knowledge, the current recycling/fabrication/transmutation mechanics available across the packs are:
- IC2 UU Matter. The recycler allows you to make "scrap" out of your excess items, which can speed up the creation of UU Matter, which can, in turn, be used to make many base materials. The recycler gives no weighting to values of an item, though, a piece of cobblestone is worth the same as a diamond to it.
- Thaumcraft 3 aspects. Aspects make up the basis of many items and, when those items are thrown into a boiling crucible, those aspects are released and can be used in the creation of many magical materials. It is possible to transmute through the common metals (including silver, copper and tin), but it is not possible to create most other base materials (gunpowder is the exception to this), and there is a cost of vis from the magician.
- Equivalent Exchange 3. The Minuim Stone allows transmutation up and down the ranks of materials (4 cobble > 1 gravel, 4 gold > 1 diamond, etc.), as well as the reclamation of crafting materials from some simple recipes, and the exchange of similarly-tiered items (i.e. between the types of wood and saplings).
- Ars Magica. This is probably the closest to the old EE2 mechanic. You are able to throw items into the "nexus" to generate mana, which can be used for a variety of things, including the duplication of many base items. There is a loss to this process, however. This mod is also not in any current FTB packs (although it'll likely be in the new DW20 and magic packs when released), primarily for the very mechanic that you are looking for.
In short, there are very specialised and lossy versions of EMC available in the packs, but the mechanic itself is often considered to be fundamentally "broken" when discussing these things.
It is, however one of the primary bases for the original Feed The Beast map and concept, so you never know, anything might happen.
Great forum and great users this far