Hi Halcon,
According to the document at
http://www.hydro-photon.com/PDF/A_&_L_Labs.pdf the 6 log reduction can be achieved by multiple UV doses even in turbid water (EPA challenge water) with UV times of around 180 sec i.e a double UV dose on the same water to be sterilised. 3 UV doses gives > 6 log reduction.
According to the document at
http://www.hydro-photon.com/PDF/CoccidianParastites.pdf the steripen outperforms MP1s for destroying Cryptosporidium even after MP1s 4 hr sterilisation period.
These are independent papers/documents.
The Steripen when used in conjuction with a prefilter such as a Katadyn Pocket Microfilter is very useful for long term water sterilisation procurement at home. A lighterweight alternative (trekking) would be to use a prefilter such as a Millbank Bag.
Being in Scotland, I can generally leave the Millbank bag at home as well when drinking water from mountain streams.