Interesting to get another view on the zerowater, always a good idea. I have been using it for a year and am on my 3rd filter. I did read about the 'fishy' smell, but I haven't come across that and assume people are just being lazy and not keeping an eye on the filter life. It will last a long time at TDS000 but when it gets to 003 (about 100L with my water) it will go up quickly after 003 (about 1TDS per litre to 006, I haven't gone passed that) so it needs keeping an eye on the TDS (but that is easy enough) and the manufacturers state it should be changed at 006 anyway, and my money would be on the likelihood that people aren't doing that, after all for drinking what is 006TDS, nothing and being too mean to buy and replace the filter cartridge when the manufacturer recommends they should!.
To sum up, I am using the zerowater AS PER THE MANUFACTURERS RECOMMENDATIONS, am on my 3rd filter (2 for the year basically) and have a tank over run with shrimp (having now to cull some), never seen a dead shrimp or any unusual parameters, disease etc and NO Ammonia. If you want to/ or have read my original first ever post (about this very subject) it is no exaggeration to say that without the zerowater filter I wouldn't even be keeping Taiwan Bee shrimp at this point, but all details are in that article. A year of zerowater with shrimp so far, judge for yourself?
https://skfaquatics.com/forum/topic/14025-tap-water-taiwan-bee-uk-zerowater/
It is always good to get another perspective though and good to see you back on here.
Simon