I am happy to be corrected on any of this but to my knowledge:
Beyonwiz are Korean, not Australian.
The same importer was importing both Beyonwiz and Topfield, but there was some fall out and now they are imported by separate suppliers. They are sold in the big retail chains, but are not huge sellers due to their high price.
They are generally quite expensive due to being packed full of features. The PVR version is typically compared toTopfield9000. There is no competitor I know of to the DVD version (which is basically a PVR, networked media centre and dvd player).
There is a local mod to the BW to allow auto download of a local subscription epg known as IceTV. This exists because until recently the commercial networks did not broadcast the epg. Even now it is flakey.
I don't own one, but have played in the shops, and they seem comparable to other networked media players. The advantage is the network allows access to the pvr files, if you want to archive any tv shows.
Generally, they are very highly regarded, and can be rated as a high end pvr.