I own a baritone JP 373 lacquer, bought 3 years ago used almost new. I can say that is a good horn; it is a Chinese clone of the Besson BE955 with the leadpipe Sterling design, made in China with Sterling England quality control. The lacquering now begins to show signs of wear, and even from new it didn't have a good finish. The valves are made of Monel (alloy composed of nickel and copper), good smoothness, almost perfect pitch ( but I had to shorten all the slides), it is still a bit hard to play respect to the euphonium, perhaps because I use it occasionally. I noticed that between the 273 and 373 models for the baritone and 274 and 374 for the euphonium there is a considerable difference in price, while for the specifications the only difference seems to be given by the material, brass 70/30 for the series 2 and brass 80/20 for the 3 series.
2007 Besson Prestige 2052, 3D+ K&G mouthpiece; JP373 baritone, 4B modified K&G mouthpiece; Bach 42GO trombone, T4C K&G mouthpiece; 1973 Besson New Standard 3 compensated valves, 3D+ K&G modified mouthpiece; Wessex French C tuba, 3D+ K&G modified mouthpiece.