I have to admit I am troubled by reading all this including that it has a half-life.. I did have the assumption that water soluble meant that excess was eliminated out the same day as is the case with some things. I had literally never heard of this toxicity issue till last night. One problem in general is that supplements don't really come in a "smaller size" unless I guess, you get powder form instead of capsules. I will have to review the genetic data I have again.
Genetic data is useful to know really, especially for people with MTHFR mutations as many pathways get affected.
Blood tests since then have shown that my B6 levels are fine with my usual diet, I don't take multivitamins or supplements anymore.
I don't know much about B6 beyond my own experiences with it, so all I can say is make sure you've discussed it with your GP, and be aware of the coasting effect if you do happen to develop any neuropathic symptoms: https://en.wikipedia.org/wiki/Megavitamin-B6_syndrome