In reality, it all boils down to what the individual manufacturer felt was the best configuration for the design. The ability to turn lose of the collective is (was) an important consideration in some designs however, ignored in others (as pointed out in earlier posts). Insofar as weight and balance, again, important considerations in some designs, ignored in others and, changed by STC and or field modifications in quite a few. (i.e., it is easier to perform external load ops from the left seat - better view, not leaning away from the collective, etc. Therefore, numerous operators have converted numerous aircraft models to accomodate left seat operations for various mission requirements - BH206, BH212/ 412, BH214, AS315, 316/ 319, on and on. The 47 had several variations that flew from left seat(most G models), right seat (some OH13), center (J models) In fact, the J model pilots sat in front of the passengers all by him/ herself. Hillers were the same with three configurations. Sikorsky bounced around with theirs as well to a certain extent as did Hughes (MD). Hope this muddies the water some more.
B. Loser