I think .15 is too slow for steering yes (I can't drive a car with slow steering). The .09's are not twitchy and can save you from a bobble/collision/pipe with a fast correction. The 2015 for throttle and the 1409 for steering is the perfect combo. If you are willing to learn to steer with a .09 (or faster) servo, you will become a better driver in my opinion.