Here's my thoughts on it. I've only used bottled nutes combined with organic once when I first started organic. I just flushed with ph'd water. No salt buildup (at least not that I could tell).
I don't know if the bacteria will break down bottled nutes or not, but what I would do is repot just before flowering and add more organic P to your soil. They will still have a decent balance as long as you add a little N, but then there's no chance of salt buildup.
Your roots are going to expand approx 2-3 times what they are during flowering. Just makes sense to repot with fresh organics. Just my thoughts.