You kind of need to quit listening to the Techs at the hydro store or were you are getting your info. All you really need is a good 2 or 3 part dry base nutrient. Mega Crop, Jacks,
Athena. Some Kelp Extract, grow more is pretty cheap for this. Monosilic Acid (not cheap), fulvic acid and some homemade hammer head.
If you do not want to go the dry way. GP 3 part is Ok, with the above add ons. If you are in soil that has nutrients in the soil cut the suggested amount by 50 present and work up from there and add Humic Acid. It will help with breaking down the naterials in the soil. You can add microbes as well.
Very very few of the people at the hydro store have a real understanding of the plants needs. It works like this. The rep for say nutrient company A shows up to the store and gets a conversation going with the techs. Gives them free product for pitching their line of products.
They all do a little something. You mentioned some AN snake oil stuff. I have used their overdrive. It has a PGR, guessing Tria. It works but they all come at a cost. IMO overdrive hurts essential oil production. If you want to try Tria get Green Planet Massive. Much more economical. But again IMO Tria has a negative effect on oils but increases weight.
I am ashamed to say it but I have tried quite a few of these snake oil formulas only to find best results with just some basic inputs. Ballin on a budget. I have even spent like 200 a liter of Green Sensation at 200 us a liter. Does is doing something Yes at a cost.
The plants nutrient needs just do not change all that much from veg to flower. Do they need a little bit more P&K in bloom yes. Hence the home made hammerhead. At 1 gram per gallon.