i just did and went with a brs 6 stage mostly cause i like not having to dump as much DI, even when the first canister of di is almost done its still pulling some out so the second finishes it off, then i replace the exhusted one and rotate them. so the first one gets new di, second on gets bumped to first position and new one is on the end now( if that makes sense). i monitor pressure levels as it drops i know pre filters are done, i also watch tds coming out membrane when tds goes up i replace it. just make sure you get a kit with pressure gauge and inline dual tds meter. also i can show you how to make your di last longer by purging tds creep.