Yes, when ASIC mining starts it will change these numbers. It's difficult to predict the change in difficulty and therefore estimate the payback period in advance of these coming online.

Once ASICs are actually producing there will likely be a leap in difficulty but a reduction in mining activity as all non-ASIC miners drop out of the pool. This will give ASICs an initial advantage until the supply of ASIC mining machines catches up to the previous level of non-ASIC mining.

Once Pyramining has ASICs in place and producing coins I'll look at this opportunity again. Until then, I'm out.