The difference between CE and a hacked Digibit Firmware is the team size. CE has about a dozen active developers which makes it relatively robust. The demand for a hacked Firmware for the Digibit would be a few dozen users so there is only ever going to be one person doing active development - that makes for a very unstable and unreliable development cycle - and what do you actually get - nothing. Your still down to a minimal two box solution because a hacked Digibit Twin running a Tvheadend server will not be able to run your CE client. There is literally nothing to be gained by going down that path - NOTHING.
I have never heard of anyone doing it anyway so its a mute point.
Shoog