[Sweets]

I'm not familiar with the first filter but no filter can remove viruses, because they're far too small. There are some filters that also chemically treat the water, usually with iodine, and they will kill viruses. Destroy them, actually, because they're not really alive. Dr Wilkerson, who wrote Medicine For Mountaineering, once stated that they used a ceramic filter in India and there were no virus complications because most viruses are attached to larger particles. Anyway, viruses are pretty delicate and easy to get rid of- in clear water- I carry tincture of iodine for that but I also like a chlorine product called 'Aquatabs,' foil wrapped tablets which are cheap and pretty stable. I never worry about viruses in wilderness water BTW, it's human waste that carries the bad ones.

The Pocket filter is worth the investment, IMO. I used several cheaper ones before I realised the things do have to be that sturdy, and with the Pocket you don't have to buy refills. I believe you'll find they're a lot cheaper on Amazon; I saved around $100.

 

[Sweets]

Actually the First Need XLE ELITE does remove viruses. It is an actual water purifier, not a filter. It is rated to remove particles down to 0.1 micron and is certified by the EPA to remove viruses (chemical free). The cheapest places I have found for the Katadyn Pocket filter is Amazon and Campmor, both under $300.
I'm not sure want to have to have to rely on additional chemicals or a fire to boil water to get rid of viruses. But if viruses are not really something to worry about from normal water sources (lakes, streams, rainwater), then having a filter that cleans 13,000 gallons is hard to pass up.

Huh, there has to be a catch then, probably related to the filter's working life (as already stated) and also the ease of pumping and cleaning. I'll stick with the Pocket, which has years & years & years of proven use the world over.