It is all so subjective really and the reality is that you will get different answers from different people. Some people will say one thing, the others another.
I think it is fair to say on the whole that 'motion' on OLED can be a bit of an acquired taste (coming from a Sony LCD it seemed a bit 'different' to me at first).
Having said that, one of the reasons that I personally did not go for a B8 was because of some of the things that I saw on the LG sets in relation to this subject. I am not in any way saying that it is 'really bad' or anything like that because I do not believe it is. To be honest I saw something on all the OLED's that seemed a bit odd but the overall gains far outweighed this in my eyes.
What I must stress as well though is that I only watch movies and did not check out any sport at all on the sets.
FWIW I think that you need to just go to somewhere like RS and watch some of this content on the B8. In all honesty you are going to be the best judge for yourself.