The drink safe DOES NOT REMOVE VIRUSES. It tries to kill them with chemical warfare. BIG DIFFERENCE.
Erm! I think you are wrong about the drink-safe system. It does remove viruses. That is according to various testing houses it uses. It is "approved" (if there really is any such approval out their) to remove viruses in Australia, America, UK, South Africa, etc. I have one in my grubby hands and reading from the label. Tested by MOD, national test labs, environment agency, London school of hygeine and tropical medicine, etc., etc., etc.
IIRC correctly another company with a similar looking filter tried to ride on their testing by saying it was the same. That could have been Web-tex but I'm not 100% sure on that. I do know Web-tex is NOT the same as this filter as this one DOES remove viruses. That's if the various reports of the test houses are to be believed. Afterall if the LSH&TM is used by both companies to test their product then surely the results for both products can be equally relied upon.
Anyway the one thing you can say is the Lifesaver and the Drink-Safe products both remove viruses and disease causes. Unless you choose to ignore tests and approvals by respected bodies and test houses.
Another thing the Drink-Safe system is a filter only not a chemical and filter system. I'm guessing it uses a similar fine pore size that the Lifesaver system uses. Its not hard to understand, if you make the holes the water has to travel through small enough it will take out the large disease causatives. The hard thing is making those filters and these two companies have managed it to a reliable level to work. That means it is down to personal preference as to which system suits you. In my case the £39.99 delivered price of the Drink-safe inline filter won over the £100+ Lifesaver. That and the 100g or so weight of it.