I have been running the Mamba and the Quark with out disabling the BEC seems the mini servos dont draw enough amps to overheat the BEC everything has been working great. :)
I'm looking at eather a 5s or 6s set up to try and get over a 100mph. :)
I'm not a big Spektrum fan for distance I get a lot more distance with my FM Air M8 set up vers the Spektrum. At speeds over 60mph I found the fiberglass antenna helps cut down the cartwheels that keep going and going and going and well you get the idea.