Update
I have now had the opportunity to do all of them at least twice, and they do work well. 'High Energy Espresso' is a really powerful one--I learned that out the hard way as I used it around 6 PM one night (I didn't sleep the night before, was on fumes, and didn't want to go to bed yet). Holy mama, big mistake

! I was able to go to sleep, though, that night...around 2:30 AM

. I really liked 'Creative Spark', 'Razor Sharp Focus', and 'Power Chill' the most. I have had 50/50 success with 'Ultra Deep Sleep' probably due to my lifelong insomnia. It is a good series for those interested for a little something extra to boost (temporarily) your performance in the aforementioned ways. It's just fun to listen to as well.
I am also reading one of your iBooks ("Secret Art of Self-Development"), Karl--it is a GOOD read thus far. I used to be a Tony Robbins' fan back when he was new (still am) and I love empowerment stuff when done correctly (used it all of the time as a manager--to outstanding results). Kudos to you.