If you are getting KO Helios, why not match it w/ KO servos. I have servos from different brands. I always prefer to match them as the center point will be closer. I have both helios and m11, and I run both brand servos. I always felt a little better when both the servos and radios are the same brand.
One thing to keep in mind is that, if u use KO/Airtronics radios, you need to servo reverse if u use futaba servos. If you have more than one car, make sure you don't have a futaba servo for throttle in one of them and airtronics/ko/hitec servo in another car. if you forget to turn off the rx pack in one car, you will fry your throttle servo. I did that.