I had a first run Shield in .40 and traded it in a few years back. I've regretted it since. Last month I came across a PC Shield in 9mm and decided to give it a whirl. 500 rounds later I'm sold.
There's definitely an improvement in the trigger. It's smoother than my standard was. The sights are amazing during the day but offer no advantage at night. I can't speak on the porting offering a more controllable experience compared to a standard Shield 9mm, but it is very pleasant to shoot. My recoil sensitive wife loves it, so we may be getting another. Within her first range session she was shooting better than she does with guns she's owned for a while.
As far as added flash being an issue, I say poppycock! Both of us shot it in low lighting and neither of us noticed anything. The only time we noticed the additional flash was when watching a slow motion video we took. Then it's possible to see the "V" flash from the porting. While actually shooting it, we didn't notice it. It exists, but in no way is it enough to cause any issues.
I feel I notice more flash shooting a 642 in low light.... and we all know how many people carry a j-frame.
I personally feel the small price increase was worth it. My wife may be waiting until she can grt her hands on the night sights model. I
Is the PC version necessary? Nope. But it's definitely nice.