The battery finally got here! Only 3 working days for the actual shipping (took them 3 days to ship it out though), glad I paid extra for express shipping (from HobbyCity.com).
It came with a total voltage of 7.75v and 3.82v on each cell. Definitely in the storage voltage range, and in balance.
I used my new, untested Lipo charger (iCharger 106B) to quick charge it at 5A up to 4.15v per cell (I lowered the target max voltage just in case it overcharged it, to be on the safe side). It took in about 2700 mAh and got to exactly 8.30v, and 4.15v per cell (without balancing), with a CV amperage cutoff at 1Amp (fast charge setting).
I put it into my MM5700-powered B4 with every option set to slowest, that is 100% traction control, Lowest motor timing (0), and 6v Lipo cut-off (this supposedly somewhat lowers the max acceleration even with a charged batt), and let it rip.
The power was absolutely incredible.
I couldn't even go at full throttle on my local street (with a 24 tooth pinion lol), and the acceleration was just indescribable.
Wasn't even pulling the throttle as fast as possible either.
I only ran it for about 12-13 mins, not race conditions, but it went down to 7.98v at the end (exactly 3.99v per cell) which means it used about 20% capacity (1000-ish mAh). I'll confirm this tomorrow when I recharge it. The Mamba ESC and motor temps were pretty hot (but in normal range, esp. with 24T pinion), but the battery wasn't even slightly warm (86*F-ish).
Of course this isn't a conclusive test, and the only other Lipo I can compare it to is a TrakPower 4900 that I've tried out on a track. It's hard to compare off-road performance vs. on-road, but I can tell this for sure, this pack doesn't disappoint. I'm sure its at least as powerful as the TrakPower 4900, if not more. In other words, it's waaay more than enough for my needs.
It remains to be seen how it will behave in race-conditions, esp. when fully charged, and running for 20~ mins at a time. It certainly isn't a dud, however, and I'm quite satisfied, considering the $105 price.