I only dry in the dryer on high heat. I don't take them out half way through the cycle and have not had a single diaper "ruined" by the dryer.
PUL is made for the mediacl community and is made to be autoclaved in very high heat. It also IMO performs better and more consistently when dried at least every now and then.
The dryer really does help the PUL more that it ruins it.
The only time you can not put PUL in the dryer is if it is a single piece of PUL the shiney side will stick together if you do this.
Also, be sure to check your wahm's warrenty, some do advise against the dryer and using it can void any warrenty.