I've seen a lot of advantages for having all stages left - streamlined, simpler hose routings, prevents laziness in tank ID etc, but haven't found many for having lean left rich right. The only ones I can think of are that it means you can use steel stages without being unbalanced, and it helps you to identify tanks in zero vis conditions (but then how would you know what depth to switch at any way?). So, seeming as a lot of people dive with tanks both sides, why d you do it?
Thanks in advance for any replies
Even with Aluminium stages it helps balance once you start carrying a few, especially if some have Helium in them. It adds another layer of protection to gas switching if you want it (although obviously it should never ever be the primary one).
Hose routing and changing over is sometimes easier as well depending on the regs especially when changing from one deco mix to another - you dont need tank cycle stuff to put the current tank on top etc.
For 1 or 2 stages i dont really see the need for LL/RR tanks but for more than that it does come in handy to help the balance, reduce the clutter all on one side and so on. I go with up to 2 on the left and adding any more start putting them on both sides for the above reasons. I can see no advantage at all to piling even more on the left or using a leash.
Id reverse the question, what advantages does all left have over a split on each? (and no, its not long hose deploy. A long hose works fine with a stage right).