We conducted blind-tasting tests on espresso and French press coffee lovers. They tasted paper-filtered AeroPress brew and metal-filtered brew made with espresso filters and custom filters which were about three times finer. Every single taster preferred the paper-filtered brew.
This is not surprising, in light of the fact that the fine particles which pass through metal filters are quite bitter.
In the book Coffee – A Guide to Buying Brewing and Enjoying, renowned coffee author Kenneth Davids wrote about making drip coffee with metal filters;
you may not like coffee made with these filters as much as you like coffee brewed with paper filters. The mesh allows a good deal of sediment and colloids to enter the brewed coffee, which gives it a heavy, often gritty taste, closer in style to French-press coffee.
Also, from the same book and page;
A note on Filter Papers
Virtually all white filter papers manufactured today are whitened without use of dioxin, a carcinogen that was used in bleaching paper through the late 1980s. For this reason, I feel confident in recommending white papers in preference to brown, which imparts a cardboardy taste to the brewed water and which may harbor some dubious chemicals of their own, including tars.||–