One downside is that you're a lot more limited in the wheels you can use.
Also once the shifting can be integrated as part of a electric groupset instead of having it's own separate satellite shifter that will make things a lot neater.
In Ridley it came plugged at the Di2 front shifter. It wasn't integrated as you couldn't see it in the shimano app but worked as a button. Anyone handy with electronics could do it.
Not sure if that's possible with SRAM or 12 speed shimano, possibly not
One downside is that you're a lot more limited in the wheels you can use.
Also once the shifting can be integrated as part of a electric groupset instead of having it's own separate satellite shifter that will make things a lot neater.