Re: Accumulation phase and rebalancing
Selling your appreciated foreign funds will create a capital gain that you'll be taxed on.
That would be a good thing if we're talking about a modest amount of money and wont give you a big hit this year...if your tax level is reasonable. You could pay niblets of the gains each year rather than in one big lump during withdrawal.
Bad thing if the gain would put you into a 30%+ bracket.
DCAing your contributions into the less appreciated fund would be a good idea.
Another small contribution would be to see if the foreign funds distribute much in the way of dividends or capital gains at the end of the year. If they do, and your broker allows it (vanguard does), set your fund distribution options for the dividends and gains to be reinvested into the US fund. Since these distributions generate taxable income anyhow, you're going to pay for them. Might as well reduce your gains from selling. Might only be 2% or 3%, but it might matter...
Be fearful when others are greedy, and greedy when others are fearful. Just another form of "buy low, sell high" for those who have trouble with things. This rule is not universal. Do not buy a 1973 Pinto because everyone else is afraid of it.