Often the materials from these items are worth so much that you will either break even or make a profit from desynthing them. At the moment as of 3. The Moblin equipment is a prime example. Sell the materials, make your profit, and level your desynth incidentally.
Like all desynthesis, skill level has relatively little bearing on HQ chances, so as long as a character has enough skill to successfully desynth one of these items at all, a HQ result even HQ3 is possible.
They are, however, a nice bonus when attempting to salvage materials back from a finished but unwanted product. Use the values of those items and the list below to determine when to switch between the following items. With extremely liberal use of materia and Tinker's Bacon, you can actually start on pentamelded HW items as low as