Interesting thought... I've had plants that are seemingly immune to hlvd/fusarium. Would be cool to use that rootstock on problematic plants to see if it has healing ability or just for ease of growth.I haven't found too much difference due to rootstock, honestly.
I do make more plants from a single pack/type than completely mixed ones, though, at least for flowering.
It's easier/more efficient to have the whole thing come in more or less at once. Holding the space for a whole plant with just a few really long running buds left on it from a very sativa scion can feel like a bit of a waste!