I think you'll get along better if your stackings are either identical or are part of the same flow. By flow I mean that certain stackings seem to have a sort of synergy, such that when they come in contact they are more in sync with each other: they draw and direct instinctual energies in the same direction. Stackings that are not part of the same flow direct that energy opposite to each other, which wears them out. It is as if they give each other jolts. Their interaction to me looks similar to pulling some fabric in opposite directions - it builds up a static charge and at some point gives both an unpleasant shock. A few observations I've made led me to suspect this and later encountered posts by dfgray and a few other people on other forums describing the same thing so guess I am not the only one seeing this.
Basically, the instincts can be arranged into two flows or currents. First current is so->sx->sp->so, while the second one runs so->sp>sx->so, in the opposite direction from the first one. The first current carries three stacking with it: sp/so sx/sp so/sx. The second current carries the other three: sp/sx sx/so so/sp. Thus the two flows are:
1st current: sp/so-->so/sx-->sx/sp-->sp/so
2nd current: sp/sx-->sx/so-->so/sp-->sp/sx
People with stackings that are part of the same flow will have more synchronous interaction since they are aiming their instinctual energies in the same direction. I've added a short excerpt about it at the bottom of this article
link along with dfgray's samsara interpretation of the stacks.