98% of the time, if a good PDR guy says he can fix it, he can fix it.
Yes, sometime the paint cracks. It happens.
Look at it this way.
He gave it a try and cracked the paint. Where did your position change? You took a chance on the more economical route and it didn't work. If it's driving you that crazy, you're going to fix it no matter what. He's not going to charge you if he cracks paint, that's a general PDR business practice.
So now that the paint is cracked, you're position in the real world has not changed at all. You still want the dent fixed, no?
You can skip a possible great economical outcome, or you can take it to the body shop and have it fixed traditionally at body shop prices. You're choice.
I can guarantee you, your body shop will probably call their good PDR guy in and have him give it a try, what do they have to lose? They're already going to charge you the cost of the traditional putty and paint estimate they gave you, no matter what.
And yes, I'm a former PDR guy. Too old and too sore to do it now. But I have 4 PDR guys that trained under and with me and I will tell you right here and right now. They are some of the best in this country at their trade so I know a little about this stuff. I invite you to look up Penske Scottsdale 101 Auto Collection and peruse some of the cars we work on daily.
Just food for thought.