Sean,
In most cases the screened fittings won't slow flow unless they are about 50% or more pluggeg up.. On the fuel side you have to be careful though ??? There are some fuel filter fittings made that are -6 to 1/8 NPT and the screen is in the small 1/8 NPT end. this one plugs with just a few small particals getting into it... Then the are the old (most common) set ups with a 1/4 NPT to 1/8 NPT reducer that uses a -6 to 1/4 NPT filter fitting. these have the bigger screens in the 1/4 NPT end...
We now have and use a -6 to 1/8 NPT fitting that removes the need for the reducer, and we have the filter on the -6 end so you can easily see and inspect it... Hope this helps.. Steve