My 2 cents worth. You don't need any sort of voltage regulator. A 6.6 Life is just fine for 6 volt rated servos. I use them in all my jets and I don't own any voltage regulators! Just another potential point of failure in my opinion. Dual battery? Be honest. Have you ever had an onboard battery fail? In 38 years, I have never seen this happen. Dual batteries is just overkill; again, my opinion. I have never used or even considered using a dual battery setup.