I am considering a mechanical breech seater for my hiwall with tang sight.  My question is which has the most
leverage in seating a bullet the cam type or linkage type?  And is there any difference in the wear of the two
seaters?  Just information between the two types I see both type advertized and I assume similar prices.

I tried a number of seaters that all twisted, bent or put the bullet in at an angle.

My scores went way up when I finally started using the Weber seaters. 

The Weber Seater linkages are properly designed (do not torque and bend), they have great leverage ability and they place bullets precisely and most importantly you can fine tune your bullet seating depth.

Go with a Russ Weber seater.

All the top breech seating shooters will recommend his seater as being one of the best.

Everything else I tried broke or did not seat the bullets properly. My scores went up 6.6 points per target when I switched to the Weber seater.