As I said in my account talk......I just saw that the new Roth TSP is coming up May 7. Unfortunately it is only for active employees and military. AND....unfortunately the rules for it really suck. I was looking forward to it, and planning to use the Roth, but now I pretty much decided I will only continue with my outside Roth IRA. See the details here:
TSP Roth Option: Questions Answered
These rules do not allow very much 'tax diversification' since you MUST start removing at 70 1/2, unlike Roth IRA. AND, you MUST withdraw evenly by %, from BOTH traditional and roth TSP. AND, you MUST put both the roth and traditional portions into the same fund allocation.
So I will use an outside Roth IRA for my roth needs!!