I'm planning on doing this sometime before EOY. I recently bought some small-value ETFs (AVUV and AVDV) in my tax-advantaged accounts and am considering expanding my small-value tilt, and selling mutual funds and waiting until the next day to buy ETFs is a bit of a hassle. I'm also considering moving my taxable assets to Fidelity because they have YTD tax figures, which I haven't been able to find in Vanguard, and I like to estimate my taxes around EOY to decide on any tax moves I want to do (I often do a Roth conversion around EOY from my old 401k rollover).
I'm going to keep a portion in the mutual fund for automatic investments, but I'll probably convert the bulk of it.