Eric, I get about 2 hours on my standard 9Z pack, 5 with my 1200mAh pack. Try this, with your antenna extended, reset the timer, and leave the TX on until the battery low warning goes off (no I would never fly to this low a point. Even then you will still have a few minutes before the thing shuts down (ie enough time to land). My feeling is that you are recharging at too conservative a point. Remember, your pack is rated at 9.6V, which is where it will probably operate for most of its usable range. Also, I discharge in this manner from time to time to double check that my batteries are still trustworthy.

If you do go with the 2300mAh packs, you don't necessarily have to buy a new wall wart, however realize that it will take 3 to 4 times as long to fully recharge.

As for lithiums, personally, I don't see an advantage in a TX. I get enough capacity as it is, and don't think I would feel the lighter weight, especially in a 9Z. Also, due to lithium's relatively volitile nature, any major manufacturer is probably obligated to put in protection circuitry for each cell as we see in video cameras, cell phones, and laptops, which would make them much more expensive with dubious benefits.