Never with a same person - it just does not work for me.

It is power-exchange, and for me, if I was given that privilege to be in place of power, I will not step down and ask partner to take my place for a change … it just does not work psychologically.

I look for different things in sub vs. Top, and while this might sound strange and just plain selfish (since I do have both in me) I prefer person who is fully "committed" to one or the other.

That being said (and I am fully aware that there is many nice people who will need to point out that this is totally un-true), all true Dominants I met in Real life have at some point in their life, or still do, submit to someone, and learned what it means to be on that end of spectrum.

So it is not question of looking for someone who is "truly" sub or Dom ... just for the person who truly enjoys being one or the other one.