re: Student loan debt pay or invest?

I would make sure to max out your 401k employer match first. I think the high interest debt has to come next (anything over 6% or so, especially if it's not tax deductible). After that, i would be sure to max out all of your tax advantaged vehicles (401k, backdoor Roth, 457b, 529s for the kids, etc. if applicable).

I'm in a similar boat as you, but have it all consolidated at 4.75%. I'm currently paying back whatever's leftover after funding all of the other stuff. I won't start saving in a taxable account until the loans are gone. I am a bit aggressive about not keeping a lot of cash on hand in terms of an emergency fund, but i have about 40k in equity from a HELOC that I've paid down, which I can tap if necessary. Also, the Roth and 457 could be tapped without penalty in case of an emergency.

Not saying that my plan is the best, but i have put a lot of thought into it and hope it helps you.