I have applied many abrasion plates on Royalex boats and have frequently not made an attempt to remove all of the vinyl. I don’t know of any that have delaminated as yet.
Removing the vinyl layer may be more a theoretical than practical benefit. West Systems does provide adhesive bond strength data for G Flex and ABS, but they have not yet, to my knowledge, done the same for the bond strength to vinyl. There is also the possibility, again in theory, that even if the bond strength to the vinyl is good, that the vinyl could later separate from the underlying ABS.
I remove the vinyl layer before patching or applying an abrasion plate when it is fairly easy to do so. I am more inclined to do so when applying a patch to an area of structural damage. The reason is that I have seen many cracks in the solid stratum of ABS that were completely covered with intact vinyl and thus were not visible.
Here are a couple of examples, This canoe had suffered damage from one or more pins. A few of the interior cracks near the centerline were apparent due to longitudinal splits in the vinyl layer, but the majority of these ABS cracks were not apparent until I had removed the gray vinyl layer. In this photo, most of the cracks have been “guttered out” and filled in with G Flex moderately thickened with silica powder:
In this photo the circular area was where a vinyl backed D ring patch had been improperly applied using vinyl cement. Most likely, the cement had not been allowed to degas sufficiently after it was applied to the thick vinyl patch before it was placed on the hull, and then either acetone or ABS degassed into the hull causing the damage to the ABS layer. In this case, the vinyl layer under the D ring patch was discolored, but intact:
In this case, none of those short cracks in the circular area were apparent until I removed the vinyl under where the old D ring patch had been,