Grip diameter is a critical aspect, not for overall control, but in hand/arm fatigue. Generally, larger grips are hard on smaller hands (like mine) - - result in premature arm-pump when riding really demanding terrain. Too-thin of grips can do similar things.

I personally find Ourys too large for my hand and they fatigue me despite their soft compound. Sunline thin grips (they come as thicks and thins) are just a touch too thin, I've found. Most optimum diameter grip I've ever used is the Yeti-logo ODI Lock-Ons.