I have the acrylic nauticam 4.33 port, and I did manage to scratch it pretty badly right dead center. The 8mm lens is really eager to focus on the scuff, especially in blue water without any other obvious subject. Whale shark coming? yeah, here's a photo of your dome.
I've managed to buff it out, but the dome is so small that it's a little hard to work on. The abrasive kits remove the bad scuff, but then leave a bigger ring of slightly less scuff, which the next abrasive can take out, but then the circle bigger, on to the next abrasive.... it gets harder near the edges to work the abrasive smoothly, and I find it much easier to do on big domes. Your milage may vary.
Personally, I'd go glass at the athena price point but not at the zen price point.