I have a Nottingham Ana-log and have it set up with 2 arms. The 12" Nottingham arm and a SME 312S. IMO, the question of which arm to use is dependant on the cartridge and type of sound you want.
I like using my Koetsu Onyx with the SME arm and the Lyra Helikon mono with the Nottingham arm. It's all a matter of synergy. Essentially, I feel the Nottingham is a slightly dark and liquid table. Adding a warm sounding cartridge to it like a Koetsu with the Nottingham arm is almost too much on the warm and liquid side. The more detailed and neutral SME arm balances things out a bit. Likewise, I find the Lyra Helikon incredibly detailed and neutral. The Nottinham arm seems to add some needed warmth and liquidity.
My $.02.