I have the scout with a Kontrapunk b. Sure sounds good to me. I also had the dynavector 20x for a while. It also sounds very good. Between the 2,you will not be disappointed.
Although I have no experience with the Kontrapunk A, I used a Dynavector 20x on my Rega P9/1000 with good results until I broke the stylus while trying to clean the table. If it is within you budget also think about the Shelter 501II, but the Dynavector is a great cart, sounded excellent with Jazz and Blues on my system.
Hope this helps. Also (not that I have to tell you but) NEVER clean a table with a cloth rag that can snag and tear off a stylus. It has been one year since the unfortunate incident and I STILL feel stupid.
MC transformers in E.A.R. 834 are nothing to write home about, but Kontrapunkt B is good enough cartridge to treat well. I would go for separate transformers in addition to MM-only 834. Ortofon should be OK on RB900, though it works better with heavier arms. You can easily add some weith to RB though.
Why don,t you look at a used ARCph3, now that Audio Research came up with the ph5 i,m sure you could get a good deal for even less money than the ear834. I personally use the tubed ph3 which has 54db gain and its no problem with my kontrapunkt A, provided that you have an active linestage. Besides make a search and you will see that the ARC is better regarded than the Ear.