The first 4.2 works, the other two don't. I forget their .xxxx build numbers.
I'm back to 3.19 myself. Waiting for official update for H2O.
I only used newer firmwares in an attempt to make my screensaver/autoshelf mods compatible. It's not like there is any difference that actually matters when reading. That basically hasn't changed in any way since I bought the device.
