Yes, it can be rolled over to an account with similiar treatment.
I had heard the term ROTH IRA PIPELINE before, but was not sure what it was in reference to.
Will have to do some digging to look at those exact numbers to understand how that process works.
I am guessing this forum reccomends that process over a taxable account through Vanguard because of the long term tax benefits outwieght the small fees?
First Roth Laddering, see get the best of both world section specifically, but read the whole thing:
http://www.madfientist.com/traditional-ira-vs-roth-ira/Second, keep in mind with your TSP both TSP traditional and Roth contributions are limited by the same 17,500 limit. Which you do depends on factors like do you think you will earn more money in retirement, and how much if at all you expect the tax rate for your tax brackets to go up. If you think you income will be higher and/or taxes higher when you are retired then Roth is the way to go, if not maybe not. Keep in mind in the 401k traditional (TSP traditional) you contribute the money before tax, the before tax money that would have otherwise disappeared is now sitting in your account earning you money which can be a big multiplier.
Additionally on the 17,500 limit (which changes, usually up, each year), you can contribute 5,500 per year to a traditional true Roth, which you can open with Vanguard. So a strategy you could take to save the maximum amount of tax advantaged savings each year like I do would to be make maximal traditional TSP contributions (17,500) and make as much as you can or maximal amount of traditional Roth (5,500) contributions.
Due to Roth laddering this the fastest path to early retirement, investments outside these vehicles should only be made once they are maxed out. Or so I have recently concluded, it certainly has multiplied my savings rate significantly.
Hope this all helps.