Hey Dias,
I'm running the same kind of idea here. I had lifepo4 big battery and it doesn't really match with my full suspended bike.
I had a look at multistar lipos and they look attractiing, beside all wjhat has been said here.
Just a hint: why not taking 2x 6s 16ah battery instead of 3x 4s batteries:
http://www.hobbyking.com/hobbyking/store/__66310__Multistar_High_Capacity_6S_16000mAh_Multi_Rotor_Lipo_Pack_EU_Warehouse_.html
I am thining to take 18 or 24s in 3 or 4 of this kind. I will probably either take battery medics plugged or a big lipo charger.
The charger you showed look sexy (the thunder one) and will surely load with no problem these 2 packs but at 300w, - edit - with 150w, it charges 6s pack at 6amps, and 16ah will take less than 3 hours.
And you will spare a headache for the wire adapter - for a close price...
Edit (again): reading this : https://endless-sphere.com/forums/viewtopic.php?f=14&t=44370
It looks like it would be hard to find a Thunder 1220 Professional...