RE: 6 Servos on a 4.8 volt, 700mAh Sport Battery???
I wouldn't do it. I would go with at least a 1200-1400. I'm not quite sure of the draw, and someone will fill us in more on that I hope, but I do know a 600-700Mah is pretty standard for 4 servos, with little draw for trainer style flying, and mild aerobatics. Add to that 2 more servos, and some decent loads with the retract operations, and you should be up at least 400-500Mah just for that. So...given 700Mah for your standard servo operation, now add...well...400-500Mah for the reserve/extra servo power,,,,,yeppers..... About 1200-1400Mah is about right. I run this in all multi-servo combo's(1400Mah packs), and it does have plenty of power.
I have that in a Midwest 27% Extra running 6 servos, as well, as a H9 Edge540 running 6 servos, and a have used it in multi-servo/retract applications with no prob. You can probably expect 4-5 flights safely with it. Always, always, always keep an eye on your packs with a good meter.
Voltage is another story, and for most apps 4.8 is fine, as you didn't say what type of plane your putting it in. The Mah that we're talking about though is capacity, and that's what you need for more then a standard 4ch set-up.