I just tried converting ta piece of the "Oktapussi" clothing set from Aiko to V4 using Evil's clothing converter, and it worked very well.  Granted, this was something simple, but I wanted to see if it would be worth buying other character clothes.  I'm going to try more complex figures, but so far, I am impressed.

As for mats, they will transfer over :D.

So, time to expand my clothing set