"I've had a couple of gore-tex jackets delaminate, but does PU?"
I have had 2 backpacks, rain pants, rain jacket, and 2 stuff sacks with PU coating delaminate, or disintegrate. Most of this is due to the fact that PU coatings are effected by moisture and will eventually degrad, delaminate, or turn sticky. Most PU coatings will fail within 10 years even if the item has had little to no use during most of that time.
In contrast I have a Gortex rain jacket and rain pant that are still waterproof and have not delaminated even though the DWR on them has failed. I also have an older Marmot ran jacket and pants that are still good.
For Gortex and Event DWR failure is the most likely thing to fail. Delaminating of these fabrics delamination is a very rare occurrence.