Coffee filters are maybe 10 to 20 micron. The Hiker is a sub micron filter, I think they are rated about 0.3 micron. I'm not sure what the pre-filter is, but I believe it is close to what the coffee filter is. So the coffee filter will make the pre-filter last longer without a cleaning, but it won't do much to extend the life of the main filter.

If you're going to boil, don't bother with the filter. Or better yet, use a chemical treatment like Aquamira. It's overkill to filter and boil, in my opinion. And chemicals are a lot less hassle than boiling. I believe the risk of being infected by a virus in the backcountry from drinking filtered water is infinitesimally small.