Similarly, 1056, WLP001, and US-05 are very different, even though they are considered by most people to be equals because they originated from the same source, they are not any longer exactly the same since yeast mutates after just a few generations by each manufacturer.
+1. I believe that Belle came from/is 3711, but it's definitely not identical by any means. A little more one-note than 3711 IMO, though I like Belle in certain cases.
I could go with that. Definitely agree that it has a much narrower flavor profile than most other saison yeasts including 3711.
Both 3711 or Belle are best in a saison with other things going on: hops, fruit, spices, mixed fermentation, etc. Thiriez Extra is a damn fine beer when its fresh, as are some of the hoppy saisons from Upright.
I've done two batches of higher-gravity saison with Belle (~7%), and both had higher-than-acceptable levels of fusel alcohol. The few that I've done with standard gravity wort have just been 'meh', but they became decent beers after mixed fermentation and adding dry hops or fruit.