... I'd add Si to this, lots of reasons, but it also helps with other nute elements metabolism, much like some of the micronute's do... Plus, coco is devoid of it totally... keeping plenty of K and SO4 available for last part of bloom, these are vital for proteins/enzymes and terp's,.... ease off the heavy P doses last stage of bloom,.... kelp or a dedicated micronute supplement to keep supplies up on those as well...
Flushing, still hotly debated, but I'm seeing more and more new articles/tests that pretty much debunk it, with little exception.... The length of the period is a big factor there it seems, as is how heavy the feeds have been, troubles with EC in coco, that sort of thing,.... Organic grows don't need it at all. Check out the Myth Buster section here on this, some good stuff to consider there! Point is to have clean, non-chemmy tasting bud-
Some good folks turned me onto a good coco info site worth a read ---
here
All this said, I'd still talk you over to the soil side!
.... caveat being if you can get truly good soil... Are you in the USA? If so, look into King's Mix (Royal Gold), this company is typically a coco specialty but they made this true soil recently. It's very good, quite light, almost like coco (it has some in it of course), holds pH well, dries fast.... Soil is simply more tolerant and flexible, less labor too....