To be clear, I did not mean to suggest that Grade cricket was de facto first class, merely to suggest that the relative strength of grade cricket in most Australian state was high compared to cricket in the UK, where there is proportionately more "Sunday" cricket - this is helped by the regularity with which proven state players play for their grade clubs.
As for the comparison with English first class cricket, I merely stated that some of the top grade clubs would be fancied against the weak counties of D2 - by which I mean predominantly Leicestershire, Derbyshire, Glamorgan. In saying that, I consider the experiences of my nephew, who came very close to playing for Derbyshire (would have debuted but for a ligament injury) but who found Grade cricket in Sydney to be, erm, shall we say challenging and spent some time in the B sides.