I wrote that review on backpackgeartest, and I used to use the Puritabs before the MP1 tabs became available.
The bottom line is that they use essentially the same chemistry for purification - chlorine dioxide - though they use different ingredients and reactions to get there. I don't see why the results would differ substantially if the concentration of ClO2 is the same, and Doug has laid out the advantages/disadvantages of this method (though I'll note that Katadyn claims that the MP1 tablets do, in fact, kill Crypto, which iodine doesn't reliably do).
As far as actual experiences go, I used the Puritabs and never got sick; they seemed to make the water taste about the same as the MP1 tablets, and the packaging (and tablet) is indeed smaller and easier to open...but also less durable.
Since I ran out of Puritabs I've used MP1 tablets everywhere I'd used the Puritabs, including sticking them in my PSK. I trimmed a bit of the edges off of the foil packaging to make them fit better.
If you can find Puritabs here, I don't see why it wouldn't be just fine to use them - but I don't think they provide a meaningful advantage over the MP1 tablets, even taking the packaging into account.
- Steve