I think the pyro 700 is an excellent choice. Having used 450/400, and now 350kv in my E5/700 (E5SS), I'm pretty familiar with power setups in that machine. Using the 400kv hacker and smallest pinion, (timing bumped a touch to slightly increase kv, but not a lot), I had 1250/1500/1750 as my flight modes. It was very happy there but I found I stayed at the lower rpms most of the time and wanted something more refined/efficient in the lower range, sacrificing the higher rpm. The 12~14 minute flights just weren't enough for me using 12s/4350 packs
. I had one of the hackers wound to 350kv, and it's not setup for 1250/1450 with another couple minutes of flight time. 1750 made the machine surprisingly fast and unless you want to do smack style 3D at ballistic revs, I don't think any more is needed.