Ball companies go out of their way to keep the reaction consistent from weight to weight.  At the very least, within the 14-16# range.  All other variables being equal, they should be very similar.

Dropping weight, however, doesn't usually keep all other variables equal.  You may throw harder and get more revs, and the speed-to-rev ratio may not stay constant.  Further, you may carry fewer light hits due to the ball deflecting off the head pin.  But you may carry more high pocket or big angle hits because the lighter weight might not drive past the 9 as easily.  Six of one, half a dozen of the other.

SH

I've talked many of old guys into 14lbs from their 16lb balls.  They come complaining that they get tired, wanna try 15lb ball.. I tell them, that is what I throw all day long and I get tired after a while, try 14lb and if you don't carry just as well as you were and not get tired I'll give you one of my 15lbs.  No one took me up on it, heck one guy came back with his wife to have me help her hahaha.  What fun.