Comparing the 2 graphs, the VTC6A should last about 20% longer than a 30T at an ampdraw of 10A down to a cutoff of 3.5V. Down to 3.25V they're almost even though.
At 20A the 30T is on par or even ahead in longevity at the above mentioned cutoff voltages.
As you can see there is a lot more to take into account than just mah.
That's why mooch (thanks a lot btw!) introduced the Watthours (wh) in his tests, because those give a much better overview over the capabilities of a tested cell.
But even though wh is a lot better than mah to measure a given cell, it's still not perfect, because wh can only be calculated at specific cutoff voltages and ampdraws.
Change cuttoff or ampdraw, and the rating is not that accurate for your personal setup anymore.