Your list is disrespectful to Alberto Juantorena. Patryk Dobek earned his 800m Olympic bronze but he was barely elite at 400mH. Patryk Dobek's 400m personal best is a good time for a NCAA mid-major conference guy or D-2 400m athlete. It is unfair to place Athing Mu in the same sentence as Alberto Juantorena. Her career is not over but A. Mu would not have won 400m gold at this past Olympic. I have made posts over the past several weeks stating I would like T&F expanded to 12 days to allow doubling of more events without schedule overlap. That is not what O.P. stated. O.P. and topic of this thread is Rai Benjamin discontinuing racing 400mH and switching events to 800m. What O.P. stated is foolish. Your P. Dobek statement, with his 46.xx 400m does not make O.P.'s idea sound. I have stated on other threads: Alberto Juantorena chose to double in my opinion as a HEDGE not to dominate. Juantorena missed 400m final, 1972. If Juantorena would have medaled, 1972, I doubt he would have added 800m, 1976.
It is okay to discuss 400m athletes moving up to 800m. In U.S., for decades up to 1978 or 1979, 440 yards was raced in high school meets. In 1970's, 440 yards was raced with one turn stagger, 880 yards was also raced with one turn stagger. When 440 yards was raced with one turn stagger, some gals & guys raced negative splits and of course many raced 440 yards positive splits. In that era, going from 440 yards to 880 yards was a smoother transition. Today, the races are very different, 400m & 800m.
I would like Olympic & W.C. schedule expanded to 12 days to allow doubles in numerous events without schedule conflict. With current schedule, Rai Benjamin remains a 400mH athlete and the discussion of R. Benjamin switching to 800m is foolish.