I'd say that there's no more need to focus on tweaking/balancing the game as much as to really try
to nail down all the broken quest scripts, missing textures, NPCs AI logic and such.
From what one can read around these very boards, the v1.6 patch has introduced a few serious glitches
while trying to fix very old ones.
A few examples:
Spoiler
* Primm folks not leaving the Vikki&Vance casino after completing My Kind of Town (no matter which path is taken)
* Weapons not being returned to companions inventory after leaving Gomorrah
* Missing textures for Novac motel's and bungalows
* http://www.gamesas.com/index.php?/topic/1212655-mass-purified-water-recipe/page__view__findpost__p__18156271 reverting to old crafting recipes
The only real "good" patch for me so far is v1.2, which came out back in December of 2010.
So long and... Cheers!