Yes this solar system if a one off so far.
See the Saturn Hypothesis where long ago the Earth, Mars and later Venus were moons of Saturn which, with the other 4 gas giants, orbited much closer to the Sun. Something happened.
War in Heaven? Exploding planets (see Thomas C. Van Flandern), Valance change?
Something happened.
The Earth was without form and void....................
How would/does planet alignment affect the barycenter? Seems it would throw everything out of wack like clay on a pottery wheel that gets out of balance and goes flying.