Checking in on methylation stories & science

Having had recent success from supplementing methylfolate and methylcobalamin (*) and in turn ordering a test from 23andMe to more diligently iron out a supplement regimen, I'd like to inquire about a few things:

- For those who have had success (in a nootropic sense) from testing for and treating methylation issues, what's your story and regimen? What benefits and/or costs have you experienced?

- It's occasionally brought up that methylation treatments are not backed up by sufficient evidence. From the perspective of someone well-versed in the area, what's your take? Is it akin to something like common nutritional deficiencies, where the symptoms are well-known and blood tests readily available, but literature is lacking on treating deficient individuals back to baseline levels and recording the results? Or is something more grave at play?

- Finally, aside from Genetic Genie, 23andYou, and Promethease, are there any other 3rd party venues worth checking out?

(*) Background context: Tested deficient for B-12 over a year ago at a time when I was consistently eating heavy amounts of animal products. Started receiving injections and taking sublingual M-B12 until mostly ameliorat…