ive only had experience with polyquest cells and i dont have a reason to use anything different. i understand that the fma packs have everything built in but the price seems a bit outrageous, IMHO. you can get 2 2s3100 packs for around $120 at cheapbatterypacks.com or purehobby.com. they both will ship by air. tear the shrink wrap off and shrink the two packs together, wire them in parallel and you have a 6200mah pack that is smaller than a 6 cell nimh. the polyquest packs are easy to balance yourself. starting from the red wire on the plug and going left to right, wire 1 and 2 are cell one, wire 2 and 3 are cell two, and so on. wire two small male pins on the end of a deans plug and when you find a cell a little off balance, charge it a little on its own. i have had little problems with cells out of balance, out of 6 different packs i have only had to balance a few cells. i use the ice charger and it works great. the 6200mah pack im talking about is used in a tc4 with a lehner 5300, it is a very nice setup cause it fits in the battery tray. it has the mgm 80 controller which has the lvc, i dont know if the uforce has it but i have one of the fma inline lvc devices and it works great. its nice because you have the option to set the lvc at any voltage you want. im my opinion, a lipo pack under a heavy load will need a 2.8v cutoff instead of the 3v. some think that is too low but its only for those big amp spikes that bring your voltage down.
so, if i were to spend 250 dollars, i would rather have 2 6200 mah packs than one. just my 2 cents. hope this helps.