You can switch back to traditional Poser Skinning on the fly. So if PML is having difficulty with Poser's Unimesh skinnig method, a user can just switch the character back to Poser Traditional skinning while working with PML.

 

As for warnings - some models are not designed for the Unimesh skinning. They may have stray vertices or bad welds that weren't noticeable in Poser's traditional skinning but would become apparent the minute you subdivide them. The program will warn you of this.  Not sure if that's the warning you were mentioning.