i think this is the "struggle" for the guy who does want to mess with advanced parameters. personally, i just try different amps until i find one that has the qualities i want. i really don't mess with any advanced parameters these days.
i do want to comment for those new to advanced parameters, that just because we have this new Harmonics parameter doesn't mean we have to use it, or that using it will give us benefits or detriments. it is a new optional control. i don't think that because we have it, only now can we achieve certain tones as compared to before when we didn't have it.
it's great to explore the possibilities of new controls given to us by FAS. but remember that we got great tones before this new control, so we might not have to (or want to) touch it at all