To get adequate service for a statutory demand, postal delivery isn't sufficient.
This is not true. The ATO - for instance - serves all of their statutory demands by mail to the address on record with ASIC, as do many businesses which issue statutory demands on a regular basis. This is one reason why not keeping your details current on the ASIC registers is potentially catastrophic.
ATO and ASIC are able to. Your own lawyers aren't.
I've been down this road many times and I've had people have judgments overturned due to inadequate service. Fortunately, once their heads come up (by way of their lawyers) we serve the lawyers. Fixed.