The M&P is quite possibly the easiest gun to DIY a wicked trigger on. And the PRO trigger still has a 'catch' during the pull where the trigger bar cams the firing pin plunger, because it wasn't rounded off. So I would have fixed the trigger anyway.
I don't like the Pro's sights. Not enough daylight in the notch.
Those are the only things you get on the PRO, and not the 9L. Why pay more?