The amp draw shouldn't be a problem, Zippy Flightmax have a good reputation.
I find that 'most' modern batteries are much-of-a-muchness relative to capacity, C rating, and weight. Unless you really need to get every last mA out of the pack, just pick your 'favourite' brand and increase either capacity or C rating.
With me I'd increase the C rating, as you a better increase in headroom for less weight increase, compared with a capacity increase for the same overall effect, (if you increase the C rating from 20C to 40C with low weight increase, will give a similar increase in headroom compared to a capacity increase from 3000mAh to 6000mA with a huge increase in weight).
Of course, if you want an increase in flying time too, then increasing capacity is the better way, just don't forget that e.g. an extra 100g in weight will require an increase in thrust to compensate.