S76heavy,
Many yerars ago I flew fixed seat, and on the odd occassion that seats were swapped I found my "balance" was not quite right and therefore felt uncomfortable. Now I move from seat to seat a number of times a day, I find handling comes naturally from either seat. I certainly would not like to go back to single seat flying again.
An added plus that I have found is that the co-pilots are far more confident as they are not in the "co-pilots seat", they are flying as p1 and so making decisions and while I may have had reason to question them, I have not found the need to override. By the same token, they may question any decision I may make, especially if it is a different one to what they were expecting. Because I am captain does not mean I am never wrong, I try not to be but it can happen and am not so arrogant that I cannot learn from a junior.