I heard the FMJ 23 at the Montreal audio show with Merlin VSMs, tube amps using Plitron transformers, and Gutwire cables and the sound was transcendent, especially while playing HDCD discs.
I don't know the CD50.
An option at about $1000 used is the EAD Ultradisc 2000, which I used to own but sold to downsize. It has HDCD and dual 20 bit dacs per channel, using a Pioneer stable platform transport. It is no longer made but can be found used (rarely). I can't imagine anyone being unhappy with the sound it produces. Relaxed, plenty detailed, great bass, and it just sounded right. Great build quality.
John Marks in his old column in TAS used the EAD and the CD-50, and if I remember correctly, found them to be comparable. Of course the D-50 has a variable output stage which is an advantage.
Happy hunting!