for the last couple years I have been in transition from 16 lbs to 15 lbs; using both weights in league.  sometimes in my sport league using both weights the same night as the lanes transition across 4 games.

it terms of the timing of swing and ball speed I see no difference between the 2 weights. 

When I returned to the game over a decade ago I started with 14lbs. I had a chronic wrist issue at the time and stuck with it even my wrist improved over the years.  During my coaching session several years later my coach notice that my speed was pretty fast and suggested to go up in weight.  I was around 18 mph down lane prior to the change in weight.

Justrico suggested going up to 15lbs and I owned 28 bowling balls at the time. It wasn't a problem getting rid of them. Sold 22 out of the 28 balls. I currently own 8 balls since the change 8/9 yrs ago.

I went up from 15 to 16lbs a few seasons ago as I was becoming speed dominant.  The extra weight kept my speed in check and helped me get my ball started up earlier with a smoother motion down the lane which improved my carry.
I've since had injuries and have dropped back down to 15lbs, but if you have the strength and want to find a way to cut down on your speed, I'd say its worth a consideration.