I have had a number of years coming to conference, including Ulearn. ePrincipals attended to hold their own pre-conference meeting and were presenting a number of workshops there.
I think its really important to connect f2f, at least on occasions, with the people you work with so these conferences are valuable opportunities for this. For classroom teachers they are a huge PD event and one that i have seen have great impact on their thinking & ultimately to greater or lesser extent (depending on the individuals) their practice.
The Ulearn media team interviewed a couple of ePrincipals you can see their interviews here