By diverting from the true Vanguard-Boglehead theory of  Index funds and stay the course edict, would it be out of the realm to consider playing the foreign currency exchanges and invest in the Prudent Global Income fund or the T.Rowe Price International bond fund?

The market in it's present state viewed by Bogleheads has been stay in the United states and don't invest in foreign bond markets where there is less transparency then home. As a result, bond funds aren't offered at Vanguard which gives merit to stepping out of the true Boglehead view and going elsewhere where the are offered.

I got beat up by Russell two months ago for suggesting the Permanent Portfolio (PRPFX) could be a divergence that might add return to one's portfolio in a foreign exchange venue. He was right in making aware the malfeasance that was present in the fund's history among other faults in the portfolio.

However, today with the dollar continuing to be weak and numerous funds capitalizing on that aspect, it's hard to ignore that maybe the heart of the Boglehead dictum framed with Taylor's 4 fund portfolio could be altered a small amount.