Droider
Drone Enthusiast
Dimension Engineering make a really good little switch-mode BEC that should be great for this job: http://www.dimensionengineering.com/SportBEC.htm
For driving HV servos, I think this one might do the job (but need to check with them first about radiated EMI levels): http://www.dimensionengineering.com/DE-SWADJ3.htm
Thanbks Jez.. got a Castle Creations 10amp 5-9v.