I got rid of my last Buescher C mel because the intonation was pathetic compared to the Conn Chu C mel that I have (although generally I am a Buescher fan and regularly play a "Big B" alto and tenor, plus a Buescher tipbell soprano). Several Buescher C mels have passed through my hands, some have good intonation and some not so good. Same with the Conns (I think Conns generally have spotty intonation versus Bueschers, with some notes sharp and some flat throughout the range of the horn. Bueschers tend to have great intonation at the bottom end on up to middle C. Then, as is typical with many saxes, middle D, E and F are sharp and yet the top end is pretty spot on. That's my experience anyway.).
What I noticed between the Conn and the Buescher was that the Conn had better intonation and a more soulful sound, more jazz oriented. However, I kept the Conn because of the intonation as the tonal difference with the Buescher was not significant. However, the difference between the Conn C mel (which I have really enjoyed for several years) and the Couturier is noticeable. The intonation of the Couturier is much better and the sound is more focused and rich (better harmonics?). The dynamic range also seems better, but that is purely subjective. I did ask another muso to do a blind listening test on the L&H Couturier versus the Conn and she had pretty much the same comment - the L&H had better focus and richness of tone.
It is a fun horn to play.