Come BRO... don't lie. You started a Facebook Fan site for those servos, got a servo mural tattoo on your back, and installed them in yer Jeep cuz you love them so much!
DOH ! Busted
If you were to purchase a high end servo, running a external BEC really wouldn't be nessasary, you'll have more than enough power and torque with the juice it would get via the ESC.
Of course, if you do run a external BEC you'll gain more power and speed due to using a full 6.0 volts or more if you choose. Crawlers would gain with this, nomal bashing you may or may not even notice ? Keeping the set up simple is usually best for most.