Personally these are my thoughts on the the two. I made the move down to 15lbs, because having a lot of friends in the bowling industry they made it seem like the most logical thing to do since scientifically it made perfect sense. The entire reason for moving down is this: By moving from 16 to 15 you gain more revolutions and control. With today's balls being so aggressive you really don't need the extra pound anymore to carry. There are even some people that have had great experience moving all the way down to 14lbs. I think for most people this is the way to go.
Now here is my cautionary tale. If you are a bigger guy, and have a problem throwing 16lbs to fast sometimes moving to 15lbs can wreak havoc on your timing and scores for that matter. For a year I tried 15lb equipment, and it just never matched up with me because of my strength. The change made me lose the feeling of the ball in the swing. This led me to having a very tense and muscled swing to make up for the lack of feeling. So, I'd basically put the ball where it needed to be instead of letting gravity do all the work for me. Muscling the ball is not a very good thing to do if you want a competitive repeatable swing. I've since made the move back to 16lbs and have righted the ship so to say.
So I'd at least give it a shot, because you never know what you might find. I mean unless your planning on going out on the national tour this year, a few months or a year giving 15lbs a shot isn't that big of a deal, and if things go south then look at it this way; you will learn a lot from the problems it might create.
