Yet another reason are the very high quality components used on the Asus boards, all japanese made caps and such which are things that might want to be considered when running the board out of spec 24/7.
Just to clarify, the I45 also uses high quality Japanese caps.
I like my board. The only complaints I have with it are consistent for all P45s, so that is more Intel's fault. But it has several nice features. The power and reset switches come in handy, especially since the power button on my case is finicky. Also to those who are bashing the 8x crossfire on P45s. Its 8x PCIe 2.0 so its the same as 16x PCIe 1.0. You really shouldn't run into a bandwidth issue unless you are using 4870X2's and then i would recommend an X48 anyways.
When it comes down to it, they are both great boards and I think its preference. The Biostar's also have a competitive price, compared to the tier 1 motherboard oems. I think if biostar keeps this up then they will become tier 1 themselves in short order.