I have just replaced my Jelco arm with the Ortofon 309D, 12 inch arm, on my Raven one. As you may know, it is the arm Thomas the designer uses and recommends on the Raven One. It really is very good indeed. The sound was a little soft, lacking definition, crispness. With the ortofon, the sound is immediately more sharp, defined and dynamic. In fact it is dynamics and imaging which is most obvious. The Jelco was not good at imaging. Listening to Verdi's Otello yesterday, with the Ortofon, you could clearly hear one singer was slightly to the Left and a few feet behind the other. In fact it represents the best defined imaging I have heard in my system.
The ortofon seems a good choice, if you are not going for a cost no object arm. I have'nt heard them all, but I have heard the Arro, SME 5 and Phantom, the latter on the Raven AC. Thomas again, said he feels the Ortofon is a few percentage points down on the Phantom and other top arms, at a lot less than half the price, at least in the UK. I am not sure of US pricing