Mixing brands is 100% fine if you mean can you take 2 different brands at the same time or one right after the other, but you can't mix them in the same bottle or anything, as ours comes in aa solution as you probably know.
And if you do grab our buy 6 special, I will even toss in free overnight shipping in trade for your writing a comparison review on our igf compared to the brand your using now! If you have legit igf then the comparison won't be much different, but if you feel and see ours to be a lot better like most people do then i would like that comparison noted for everyone to see.
We have loads of guys who come here and can't believe the difference between ours and the old brand they used, so its my challenge to you if you do buy ours and use it after using your current brand i will ship it overnight absolutely free!
I don't normally offer this but since your currently running someone else's i think it would be a great challenge/comparison!