According to Terrence Parker, the problem with the Ortofons is that they're made to mate with the European-version tone arms for 1200s which are slightly different than the American tone arms, with respect to the contacts.
The Ortofons have cone-shaped contacts which connect at the tip of the cone with the flat contacts inside the tone-arms. This does two things: wear a divot in the center of the contact, and put strain on the screw-down mechanism that holds the cartridge in place. After a while, the screw-down gets stripped out to where you don't get a solid connection any more. The only solution when things go wrong and spitting on your cartridge doesn't work any more is to replace the whole tone-arm, as the contacts inside and the screwdown can't be replaced separately. You could also improve matters by sanding down the contacts on the Ortofons, but I'd be scared of mucking this up!
