This may be too much of an ask at present, but I would dearly love if a colony's mineral, industrial and potential naval situation would influence likelihood of rebellion.
Even better, if several colonies relatively nearby one another (say, within two systems? or some other such limit) both run the risk of rebellion, maybe they would have a chance to pool their resources for this calculation and both end up as part of the same rebel empire. "I have neutronium and duranium, you have gallicite and shipyards. Separately we would be crushed, but together we could stand up to the tyrant!"