Siamese, definitely not Chinese. I'm quite sure I read somewhere that they do eat slime coat once they get older.
I have an SAE in one of my poly tanks right now and it's working really hard at that algae. (It's way too big for my polys to even fit it in their mouths.) My lighting is quite dim, I don't keep it on for more than 6-7 hours a day and I do water changes often to keep the nutrient level down but I still have too much algae for one SAE to handle. I'd like to get two more but I wanted to double check I'm not just lucky that the one I have hasn't attacked my polys.