Obviously there are many that prefer to avoid the P-lip, but I'm a huge fan, and have strongly considered ONLY buying them from this point forward. That being said, my potential issues have always involved the tongue, and never the roof of my mouth.
In addition, I spend a lot of time clenching and not holding my pipe, and a fishtail usually gets to my tongue in a clench.
Finally, there are significant differences among various years with the configuration of the P-lip, (in my experience) especially in width, and somewhat in thickness. For me, the newer acrylic P-lips are wider and enhance my grip and comfort by an extremely large %. The older ones seem to "roll" in clench a little more because they are narrower.
All in all, if you've a P-lip you want to get rid of, I just might like it well enough to purchase it.