Like I said in my review thread, I use 5-8 brightness level and 5-8 volume level. I'm also experiencing a increase in battery life after 2 discharges.
So that begs another question: did you guys charge/discharge your players several times when you first got yours and did you notice any improvements in battery life?
The V9000HDG only has a 2050mA according to ainol.com while the V6000HDT has a 2500mA and is also more efficient.
Hmm well that might explain the 6-7 hours others with the V6000HDT are getting vs. my < 5 hours (currently).