I found the XP DS1510MG servo to be...relaxed
. I had the pleasure of using one in a ST. Tough as all heck. I have used a few, so called, 0.15 sec 60° @ 6v servos before. That's the cutoff number/spec for me, but the DS1510MG felt slower than specs would have it.
You can almost be guaranteed it will be the same servo included in the T4.3 seeing that most of nothing else has changed 
.
EDIT: A Reedy 0712MG Digital HV Metal Gear Servo, with 7kg of torque is included.