This is also a thought process and feeling Ive had regarding perfect left/right balance. It certainly couldn't hurt, and probably helps, but all my limbs are generally doing completely different things, even at different dynamic levels. But having the full range of my strong side on my weak side as well would be great, its just not going to happen. My right is very much stronger than my left and more agile, and everything good for drumming. Ive simply trained my borderline gimpy left to do a job the best it can, god bless its deficient soul. Ambidexterity would be killer on drums, but it simply isnt one of the gifts I was blessed with. I do have the best musical taste of anyone Ive come across tho ; )For the four-stroke roll I've always been more comfortable starting with my right hand (rlrL). It took me a long time to get the reverse direction comfortable at all. I haven't found any pattern with my students as far as which direction they prefer compared to their dominant hand. It seems random so far.
I'd also disagree that both hands need perfect balance in abilities (if this is about drum set). I'm sure it works for some people, but I've abandoned that concept and it has actually helped my playing. I just recognize that on the drum set my hands generally have different roles. My right hand has more speed and finesse for right hand patterns on cymbals, while my left hand more power for cranking consistent rim shots.