There's actually an article out there that I think might determine whether that imine is stable, albeit in a roundabout way; a friend of mine might know where it is so I'll see if I can get ahold of it.

But yes you're absolutely right. Were I to illicitly make meth, I'd probably do a p2p if I was lowscale and an RA of methylamine if I was high scale. I hate admitting that bc it's the exact same route they did in Breaking Bad and it's just so cliche.

For now we have this; it doesn't specifically mention whether that imine is stable or not (or maybe it does; I don't have access to the whole publication), but it at least determines the overall route could be done.
http://pubs.acs.org/doi/pdf/10.1021/jo00105a003
http://www.tcichemicals.com/en/ru/support-download/tcimail/application/101-13b.html