Thank you for the explanation, I understand now that it's mainly about the practicalities of applying the paint. I've used Tuffcab on some baffles (as it was all I had around at the time) and agree it's tricky to get a consistent finish on the edges next to the grille batten with the roller. I also fit the port before painting, but as you say it's all hidden behind the grille if one is fitted anyway.