GSE vs Iodine for water purification?

I've used GSE on a couple of trips--a five-week trip to Ghana, three months in Bangladesh and now five months in Nepal. I've only used it as a supplement, not as a water purifier (I either buy purified water or use a filter). I take about 5 drops in a big glass of water (more than that and it's just too bitter to drink), at least once a day, sometimes several times. I've never gotten any serious intestinal bugs, although there have been 3 or 4 times in the past 7 months when I've had somewhat loose stools for a few days, but nothing that sent me rushing to the bathroom (sorry to be a bit graphic). When that has happened, I've tried to drink 3 or 4 glasses with 5 drops GSE per glass for a few days until the problem passes--pun intended. I don't think I can ascribe my intestinal health solely to GSE though, since I also try to be very careful about what I eat and drink. I checked the link of #6--pretty scarey--you can't trust anybody anymore, including the USDA, who, when they were creating their guidelines on what is and isn't organic, decided to allow "sewage sludge" to qualify as an organic fertilizer. After huge public outcry about this and other questionable judgements, they took sewage sludge off the organic fertilizer list.

If you want a purifier, I used Katadyn's X-Stream on my trip to Ghana. It has a 3-part filter, including a part that kills viruses. You can just fill it with water from anywhere--a tap, a stream, etc. REI, a supplier of sports equipment, has good info on their website about water purifiers vs. water filters. I found it really helpful when trying to decide what kind of water treatment I wanted to use. Their web address is rei.com.