How could T9 be better when it has no defense what so ever and way less cargo?
you can max out a t9 for 2/3 CR of that corvette, run a class shields and scb - you can even slap armor on it. you'll end up having 100 T of cargo less, that is 100 k -250 k less CR per run, and nothing will be able to take you down before you highwake.
that trading corvette above can't "defend" itself neither - it can fire its turrets, till it highwakes out. the t9 does the same.
if you loose your corvette (372 mj shields ... no scb... less then my courier ...), you'll loose 10 mio CR in insurance. that is 40-100 times the profit, you make more in your corvette above a t9. so - loose it 1 time in 40-100 runs, and you would have been better off with a t9.
that is the way i think - and i'm a big fan of playing around with ships, outfits, and using "the wrong ship for the right job". a trading corvette sound nearby as cool as my trading cutter, but i would always take a t9 above such a build.