I run Pulse 6s 4500mah 45C packs, fly great! at 2500HS i get about 3:30 flight time, could get 3:45 but packs are 100+ flights each.
Great power.
I ran my buddies worn down puffing glacier 6s 5000mah 45C packs and couldn't tell a difference, came down same voltage etc.
I recommend 4400-4500mah or so for 6s, lighter and same flight time from what i've heard.