I think it's a fine idea.
Some filtering is almost always better than no filtering.
I just wanted to point out to others that there may be cheaper and easier alternatives. And I wanted you and others to also understand that there's a difference in how filters are rated especially if they are designed for different things (drinking water vs shower water). Something the writer of the article and BYO magazine apparently don't know or failed to consider.
And how someone should go about testing the effectiveness of a filter.
Here's the thing a carbon filter will filter rust and sediment but it's designed to absorb chemicals such as chlorine. Pretty soon the rust and sediment will encapsulate the carbon filter particles and render them ineffective. A rust and sediment filter on the other hand is a membrane type filter designed to trap solid particles this type of filter can be backflushed a number of times without losing all of it's effectiveness.
Plus I'd hate for you or anybody reading this post to think they really could get 20 years out of a water filter. Or to drink the water out of a filter that old.
I my younger days I had a class 2 water treatment lic. So I have some idea of what I talking about with regard to water treatment. And I wanted to share that knowledge with others. Just like you wanted to share your experince of building the water filter with others.