you know this really comes down to trial and error and personal taste
to me, i liked the "pop" the -15 gave
i didn't care to much for the -16, but again personal taste
i myself felt a difference between them, especially coming out of a deep sub
i don't think you can go wrong with either one, and Dave is usually good at repitching if you need to or want to
I also felt the ski more stronger in the mid and upper with the -16, not exactly where i wanted it
the -15 had more low end pop over the custom 13-15 solas Dave setup for me
i can probably break the -15 loose with my current setup if i whack the throttle wide open, but then again i am running well over 200 psi on a 5mil
i've tried many props/pitches/cut backs to set it up the way i like it, and right now an out of the box -15 is pretty hard to beat.
also keep in mind, i am WELL over the 200# range, probably closer to 3+ with gear on, so it works for me