Just in case, however, how do you think I should tackle this issue should it rise? Should I use them all via the FX loop to avoid it or should I do something different?
Well, I'd probably arrange things as I'd ideally want them and see if any problems arise. But it could be you might need to try a few different permutations out just to be sure how you'd ideally want things anyway.
In any case we assembled a lot of information about the Pre / Post functionality in this help video:
But as you mentioned, people were able to make good use of all the effects in the H9 before the pre / post feature, and maybe, you won't need or want that extra complexity.