Wondering why some of the models use the former vs latter etf. It looks as if USMV has tighter b/a spreads, bigger aum, bigger adv and arguably does a better job at the low vol factor.
You are right, the USMV ETF did perform better than SPLV during this year. There is no problem to use it instead of SPLV. We choose SPLV because it has the same underlying 500 largecap companies as SPY. The MSCI USA includes also midcap companies.