@drbond for a man that says he knows little about turntables - I commend your choice in the Dohmann Helix.
I've heard three vinyl front ends that have stuck with me. One had the FM Acoustics phono stage in a live v recorded demo and nothing i've heard comes close to reproducing with such accuracy. The Constellation was wonderful too the kind of sound one can live with forever - powerful and fast but musical too. Finally one by a British Designer Graham Tricker called Tron - just very very musical. I've sadly never heard the Mares Connoisseur nor the Boulder. I use a Vendetta (voiced like Connoisseur) and a Whest. I envy your task in choosing - but like @rauliruegas - if it were my money? FM Acoustics - versatile and just plain brilliant.