I just started taking Xtend nearly 2 months ago...and I can't train without it. Constantly having that flow of amino acids going to your muscles throughout your workout and all day long is beneficial for repair and recovery. I sip on the stuff all day long.
I especially find BCAA's to help when adding cardio into the mix, for instance after your strength training. This aids the body in not hitting a catabolic state, or for using up nitrogen stores for energy.
Personal proof (subjective here) was I noticed that during my longer cardio sessions, while sipping on Xtend, I was not getting that "amonia" stench you may sometimes encounter when enduring cardio for too long (especially while on cuts/empty stomach cardio/post weights). This is the main indicator of a negative protein balance...meaning using protein/muscle for energy...hence catabolism. While sipping on Xtend during my workouts and then during cardio, this has not once happened to me, no matter at what intensity.
I am a firm believer in BCAA's...and apparently Arnold and all the guys used to use them...and I think they looked alright...lol.
Everything is worth a shot, and for 20 bucks...you can't go wrong! If anything you will get something that tastes REALLY good to drink all day, lol. Good luck with your training and gains!