OOPS my bad, but not really. The 4805 claims a 2000:1 contrast, and the H31 claims a 3000:1 contrast. But lab tests in all manufactures are different, and there is no real standard. Being they both have the same exact HD Dark Chip 2. There would be slight differences in the iris, but I have read many reports of claims of contrast.
I have seen a DC3 claim as low as 3000:1 and a Yamaha DC3 claims a 5000:1 using the same chip.
A higher contrast is a good thing to have, but there are to many lab factors that claim differences. Sim 2 is way underated in their contrast using superior optics, over some of the competition that claims higher numbers with the same chip, and optics that are good or equal to the Sim2's.
So once again, IMO the 2 projectors, are very alike. And you are sure not to go wrong with either.