Do you think it is worth it?4000 mh

i'd rather get (and have) a good field charger (like the sirius pro for $120.-) and charge up between flights

Its 7.2 volt for one, and that just wont work, and if you put a regulator to get it down to 4.8 you are just wasting power. I use a 3000mah pack of NiMH cells(4), and it works great. It weighs a little more than your standard 1300mah pack, but it will run way more flights, and it only cost 27.00 for them to make it for me. I aslo get the added protection of having them do a couple more welds on the tie bars, and double wraping the pack for me.

That is the same batterys Curtis and a few more have been using for about 8 months now. You will also need the charger that is required for them. From talking to pilots using them you can charge them with there charger in about 2 hours. Using the 7.2 volt pack with a voltage regulator set to 5.2 volts, you will have 5.2 volts supplied to the system the first flight of the day, you will have 5.2 volts supplied to the system the 10 flight. The servo speed and torque will stay consistent since the supply voltage is staying consistent.
You might want to look at the Duralite Plus batteries now available. They are the same technology and they have some package deals.

David