I'm really surprised the 25 Souper never took off, but I guess with the .243 pretty near killing off the .250-3000 and the .257 Roberts in the marketplace no one figured a .25 medium case of any kind was worth pursuing.
A .25 Souper Improved with a 28 or 30 degree shoulder would trump the .243, .250 Savage and .257 Roberts in one fell swoop.
IMNSHO, of course.
Gunnery, gunnery, gunnery. Hit the target, all else is twaddle!