This feature has been great and has really encouraged me to Spiritbond A LOT more. I always keep an extra set of Zelkova accessories on me now and melded twice with the cheapest crafting materia I can find. When they are done SBing (which goes pretty quick by doing batches of molybdenum ingots, palladium nuggets, twincoon thread/cloth, gazelle leather, etc.), they will produce at least a T5 and occasionally a T6, which for the moment is still going directly into my new Ali Mhigan gear open slots. This costs me next to nothing, and so I don't have to be rich to afford these Materia! I am just waiting on more Control +10s and since the recipes all this effort is for are not even available yet, there is no rush.
Here is my gear so far:
http://ffxiv.ariyala.com/13SY8
As you can see there are many open slots still but since this gear is better than the i290 stuff, crafting the top gear is still easier than it was before even though I could already make it HQ. So why rush to fully meld???
The exceptions are my legs and feet gear. Since they are the easiest to meld nearly full stats on, I have 4 melds on them, and the 5th slot will probably be 4 CP. I don't think I'll miss 3 craftsmanship or control on those...
The body, gloves, and head will probably want a T6 in the 3rd slot, so those will take a bit longer. And as you can see, I still need (2) control T6s for the gloves and body... And these are also most customizable for overall stats. I will want to wait for new crafting recipes before overmelds.
Anyway, all that to say: don't rush into all these melds and you can save a lot of gil (which is why we craft right??), and SB for your own free materias, and thanks for the new guide Caimie!