If your plants are healthy at harvest, you're probably getting the most out of your genetics quality-wise. In terms of yield, some fertilizers will do better than others. It takes a bit of trial and error but use what works best for you.
How big of difference can nutrients make from a yield standpoint. Is it minor or are we talking like 20+% increase?
Put it this way; I tested Advanced nutrients Connoisseur against DynaGro and DynaGro yielded 25% more. But it's not necessarily the brand that makes the difference but the NPK ratio. AN and dirtysnowball seem to agree that a diet balanced towards K is important, but potassium has little to do with fruit sets and flower production. If you want good yields, a balanced ratio of about 1-3-2 for flower will give excellent results.
My hydro plants get pretty sloppy late in flower as they tend to want to fall every-which-way when putting on weight like you describe. I'd either suggest tying them up or look into trellis netting to support all that weight. It may be too late to add the netting so I'd start tying them up to support those big flowers, they're only going to get heavier in the next 20 days.
25% is a very big difference in yeild! Do you feel that those nutrients are pushing your genetics to the highest yield possible?
can be a great learning experience when expierimenting on strains
That depends on what you think the limit on yields are. With my situation being a standard overhead light, 1 gram per watt is about as good as I can hope to do. Add in light movers or vertical techniques and that kind of changes the potential. But given my style and environment, that NPK ratio seems to work great for maximizing yield in my space.