Resources are only part of the equation. ARZ is a producer, and as such carries a premium. I've posted the following approach before, it's not mine (see link) but I think it's an interesting model.

The model comes from this location.

Value per oz production: $3000

Value per oz reserves: $200

You can make it more complex as per the article. In simple terms for SGR:

$3000 X 40,000 (prod est. 2008) = $120,000,000

$200 X 2,300,000 (res. est. 2008) = $705,600,000

Total= $825,600 / 250,000,000 (shares) = $3.30

ARZ:

$3000 X 160,000 (prod est. 2008) = $480,000,000

$200 x 2,300,000 (res as posted) = $460,000,000

Total = $940,000,000 / 153,336,548 (shares) = $6.13

So, ARZ looks like a good buy with this approach, SGR looks better! Ramp the numbers up/down/sideways, its the approach that matters. FWIW...rational