Conclusion

With the Crossfire XPRESS3200 ATI has delivered what looks to be a top notch chipset for enthusiasts and gamers alike.
The biggest gains can be expected in situations where the PCI-E bus is highly loaded. For example when running an X1600 Crossfire setup. Two of these cards can be had for about $250, put them in a XPRESS3200 motherboard and you get a high performance rig for a very good price. Not only does RD580 offer superior video card performance, it also offers great headroom for overclocking and a lot of options that can be tweaked.
However, if you already own a Crossfire capable setup I don't think you should upgrade to RD580 right now. But if you are looking into running Crossfire in the near future, put a x16/x16 motherboard to the top of your list.