Kurt never made Chocolate Salty Balls, did he? No... that was Chef, of course! :D
But, in all seriousness, I never actually used this feature in SoulSilver despite being enamoured of it when playing through Gold all those years ago. I actually kinda forgot about it until I read this thread for the first time a few days ago. Having said that, I only really catch Pokemon that I'd conceivably use on my team, and it was just easier to buy a fair amount of Great/Ultra Balls as opposed to waiting a few hours for a custom-made ball, no matter how cool it is.