I will start with I am by no means a lipo expert.
I picked up a 3s 4k (11.1v 4000mah) Traxxas lipo and have been ran it a few time. I only have some 2s 6k 28C SMC hard case to compare with.
The fitment is great. The semi-rigid soft case fits very well in my Stampede 4x4 and on-road slash 2wd (STRC LCG conversion using Rustler/bandit chassis, 30 series road rage, beetle body). I do like that there are 135mm and 155mm lengths available. The 155's will allow up to the get most mah in the e-revo/e-maxx battery compartments.
I have not run 3s before but there is tons of power. I have a VXL in my stampede (geared 9/54 with big crawler tires) and 3800 SCT setup in my onroad slash (23/86.) The 3s really brings the VXL alive, a little too fast for my trail-rig set up on my stampede though.
Most of the running has been done in the Slash. I started with 28/83 (gearing I found great for 2s) but ESC ran hothot after 5-6 passes. It flew but the sidewinder got hot fast. It is a true 25C battery (100A cont). Regeared a few time and found 23/86 comfortable for temps speed and run time. This also for the reduced amp draw break in in the instructions (5 runs no more than 70% amp rating)
Temp gun battery is dead but after non stop speed passes I would say 150 motor and esc and maybe 100-105 battery at 90F ambient. It does run quite a bit cooler as night (colder tires, less grip, less motor load). I will say the 2s SMC ran cooler, even at 28/83 gearing. But those are 150A+ packs VS a 100A pack.
Ran it til the LVC kicked off at 3.3v, cooled , and charged back up to 3900 mah. A true 4k pack.
I will be buying a pair of the 2S 7600's for my EMBE.
All in all a great pack. Good power and price. Cannot beat the 1 year warranty, plus lifetime replacement at 50%.