I've never used a kayfun so I can't comment on that.
Making your own juice recipes. Hmmmm, I've seen it written, and it makes sense that juice recipes are just like dinner recipes to an extent. When you're making a roast, you have an idea what the beef tastes like. You know what's gonna happen when you add salt and pepper. How is adding celery and bell pepper gonna affect the final outcome? Parsely? Thyme? Garlic and onion?
In principle at least, juice making is the same way. You have your base "meat" if you will, say, a cheesecake. Now you don't want just a plain cheesecake, you want a strawberry cheesecake so how do you get that? You add strawberry of course, but how much? And which one? The only way to ever know is by trying each iteration to know which one gives the taste you want. Knowing what your flavors taste like standalone will give you an idea of how they taste when added to a recipe.
Cooking and juice making aren't hard, but being a chef or a mixologist requires a lot of work and experimentation. HIC, who hangs out in the DIY section is such a person. Now he pretty much restricts himself to FlavourArt flavors for the most part, but I guarantee he can tell you every little nuance of just about any flavor he uses because he's worked with them so much.
That's why I said find a recipe or 2 you like the sound of and get those flavors. Mix em up and if it's too strong, or not strong enough, adjust accordingly. When you go to cooking school you don't start out on the first day creating recipes. You begin by learning proper use of the tools and ingredients. After you master the chef's recipes, then you have the background and the means to create your own. Juice mixing really isn't any different.
So, don't stress over it, and don't get overwhelmed over nothing. There are plenty of really good recipes in the DIY section and if that's not enough, the internet is full of them. Once you can walk, running isn't far behind.
I sincerely hope this helps you some, and I hope you take it in the spirit it was offered - not to discourage you, but to give you a starting point which, unless I grossly misunderstood you, was what you were looking for.
And one last thing, these comments are simply my take on it, and not necessarily that of VU forum.
