Madfloyd,
I own a Raven AC and I use a new version Ti-Planar Arm with a Transfiguration Orpheus Cart. Before purchasing, I visited Jeff Catalano at Highwater Sound in NYC. Jeff usually has 3 or 4 arm/cart combinations on his Raven AC. I heard at that time the Graham and the Tri with different cartridges in each. The differences? Since there were different cartridges in each arm, that's almost impossible to answer. However, in general, I felt the Graham was very sweet sounding with fine transparency but a slightly narrower soundstage than the Tri-Planar which I found to be more dynamic with a shallower but wider sounstage than the Graham. Take your pick. I agree with Thom M. in that arm/cart set-up are paramount along with cart loading and gain matching. Without close attention to these parameters, it won't matter what you buy since it will not perform to its utmost. I recommend a Wallytractor for your arm, although as threads of the last few days have shown, buying one is next to impossible leaving a Mint or Dr. Feickert as the next best thing. Regarding set-up, the Tri-Planar is relatively easy to set up and while I have no experience with the Graham, most reviews have indicated it is simple as well. BTW, the surface on which you rest your table may have as much impact on sound quality as your arm/cart combo not to mention the quality of your preamp and the rest of your system.
Best of Luck
