As far as I can tell, all of those cases have some dustfilters but not on every single intake point. You can add/make dust filters. I have the HAF-922 it is a great case.
If you love the c70, and are not overclocking the GPUs too much, I don't see any problems. It looks great and is solidly built and was one I considered for my build.
but even if i do overclock...increasing the fan speed should fix the problem rite?