I only use GB casually, and use the ores on my jewelcrafter to make gold I need for playing my toons. Gatherbuddy is only a very small part of the way I utilize honorbuddy. I also use it for levelling, raiding, farming honor. So yes, for me it is profitable. I think you should rephrase your question and be more specific about that you are targetting gold farmers with this question, and whether the profit of gatherbuddy gold vs banned accounts is worth it, since I'm guessing that's what you're aiming at, but I could be wrong of course.
I only have 1 WoW account, and it got banned a couple of months ago when I got greedy and farmed ghost iron ore for 18+ hours. I got banned and lost all my toons and gear. Now I bot a lot more carefully, especially, let me repeat that, especially when using GB. I got plugins that play sounds when I get whispered/mentioned that I never used before I got banned (botted 2 years flawlessly before that), and I bot for a maximum of 8 hours a day now. I still only have one account and leveled up my toons again thanks to honorbuddy, but I am a lot more careful.