I realize this may not directly answer your question and I apologize up front.
I'd highly recommend firing a round that does the following, in this order...
1. Functions well in your pistol.
2. You handle the pistols recoil well with the round in question.
3. You practice with the round in question.
Heavier rounds have two basic tendancies when it comes to reliability.
1. They function the recoil operation of the pistol well, because of slightly heavier recoil.
2. They are slightly wider to length near the tip than lighter rounds, which may cause feeding issues in short action pistols.
Now, that being said, shooting defensively has much more to do with putting rounds on target in critical areas than it does with what round you use. Putting rounds on target repeatedly has much more to do with what round you use. You can have the best wizbang round out there, but if you can't hit with it, it's as useless as a spitball.
The difference in recoil from 115 to 147 is noticeable, but manageable. I'd go with what you can shoot more effectively.