I kinda looked into this matter a little bit. What I found is:
(1) After pentamelding, an i320 has much better stats than the augmented i330. This includes better control, better craftsmanship and most importantly better CP. This came to me as a bit of a shock, since I was expecting the i330 to have at least 1 better stats (e.g. control) than the i320 despite having less CP and less of the 3rd stats.
(2) They did reduce the amount of yellow scrips required to get i300. But when you are upgrading it to i330, the amt of yellow scrip is still pretty substantial. (e.g. i300 tools used to cost 1300 yellow scrips. Now just 500-ish in patch 4.2. But still, need another 700-ish to upgrade to i330.)

So I agree with all of you (Elamys, Alien_Gamer, Faeon). I don't think it's worth the time to grind yellow scrips for i330 (especially because they're class-specific). If you already HAVE the yellow scrips to spare, and you don't have enough stats to craft your own i320, then sure, why not boost your stats a bit and grab a piece of i330. But still, it's just a stepping stone, so don't overdo it.

I admit that overmelding can be expensive, but since we now have the flexibility of removing materia. One can now meld whatever he/she can afford on Tier VI first, and then just cheaply overmeld some Tier 4 CP materia. Later, remove those CP materia at 100% rate, and re-meld again with Tier VI or Tier V.