I'm no expert, but i do have some experience with these funds, I opened a brokerage and roth ira account at this site about the time these funds got started. They do trade online without commisions for schwab clients, have low volumes and move around quite a bit from $25.00 to $26.00 so far, often trade at a discount/premium range from -0.30 to +0.50. There is a lot of opportunity to play the swings at no cost, work off some trading limit frustrations with little expense or risk, hold the tsp more a bit more conservative for the larger moves.
Although not an exact correlation, i have been treating the funds similar to C S & I, convenient without having to adjust research, strategy, or gut feeling moves very much.
SCHF = I fund, foreign exposure.
SCHX = C fund, large cap fund.
SCHA = S fund, small cap fund.
I haven't played around with SCHB = C+S total market index, more of a buy and hold allocation, i have tsp for that.
The new ones SCHV and SCHG split the large cap SCHX in half for value or growth allocations. Also there should be two more foreign variations coming in january.
Nothing fancy about these funds, but they have low expenses and trade commission free, if nothing else i have gotten a good education about how the brokerage site works, how to use market and limit orders, and have been growing non-tsp balances with regular payday contributions, i got nervous about future tax exposure a while back so limited tsp to 5% plus max match and have been diversifying a bit.
I especially like the buy/sell now and know the price you get aspect of the ETF's vs. make a tsp move by noon and hope things end the way you thought they might.
I've been nailing 1-2% gains with some regularity, not very sophisticated but also not much risk as trading fees would eat profits on other similar investments.