Some of the lower channel Futaba TX (4C, 6EX etc) come with the battery section built for 1.2v AA size batteries. If this is the case, traditionally you were stuck with the AA type. That is because the thickness of the battery compartment is only one AA battery thick. The battery packs mentioned above are also built from the same AA batteries but the batteries are stacked in two layers and wired together. That is why the cross-section of the packs will be thicker than the space available in the battery compartment, so you cant use them. However, recently I saw NiMh packs from Hydrimax on Tower that have the batteries arranged in a flat pack, you could use these if you have the Futaba J-plug in the TX or could solder in the plug yourself.

Personally, I dont think the 8 seperate AA batteries option is bad. It means you can use any reliable and cheap rechargable AA cells set available locally instead of the expensive ones from the hobby shop and you can use lower mAh capacity (meaning they will have more usable life). Also, you can keep two sets so that when the voltage on the first set drops to 9V (which you can see on the TX LCD) you and swap out and continue flying. Just remember to replace the cells between flights, buy all 8 Nos of the same make and capacity and stay away from the cheap chinese stuff. Also, keep an eye on the amount of time they last as even if one cell in the pack goes bad, you will get a reduction in the time they hold charge and you will have to replace the entire set

Ameyam