That's very true. My acrylic tanks are scratched a lot. You can't see them when the tanks are full of water however....but yeah, acrylic scratching is a major downside to it. If you know where to look you can find them though. Most of them can be buffed out, but it is indeed a pain. Plenty of upsides to acrylic though.
Kev - as I say, I'm not sure about each individual tank, so the tank you are looking at may well come with externals, but at least you know how the hooded ones look and operate now.
I know many of the extremely large SunSun and Jinlong tanks come with externals, so yeah, you could be right considering the size.