I recently swapped my nimh pack for lipo to save some weight. Since I was going for a weight reduction I didnt want to run a regulator. Using a regulator is recommended but not necessary in all cases.
I assume you already know you will need a charger capable of charging lipos but it is also advised to get one with balance capabilities. Lipo packs dont have to be balanced but I hear it will increase their life.
I have been using a lipo TX pack for the past couple years without balancing and it was never a problem. However now that I have decided to go lipo for my RX I went ahead and got a charger that balances the cells. The difference being the TX only uses a small amount of constant power but a RX will use a much higher inconsistent amount.
Other than that the only other thing you need to be made aware of is the fact you cannot run a lipo dead. If you fully discharge it you may as well throw it in the trash because it will most likely be ruined. I have read not to run a pack under its rated voltage meaning at 7.4v it is necessary to recharge a RX pack and at 11.1 for a TX pack.
They say a lipo pack will actually perform about 15% better than its MAH rating because of the voltage. I have the Losi 2000mah lipo RX pack and I figure it ought to last near 2 full hours on a charge safely. Its nice knowing I can go club racing and not worry about recharging or at a big race I could probably do a couple bump ups without any worry about the pack going dead.