Again I don't use the platform, but the lack of negative ratings is a plus. They appear to have recent trades but with minimal messages left. I clicked sell just to see what rates they are giving and it seems to good to be true. So I wouldn't risk it, now that might just be me not being familiar with the site, maybe it changes when you try to engage them in a trade. I wouldn't risk it, I would try my earlier suggestion and find someone on forum who wants to do this.

Edit: You are also outside their trade limit of a minimum 500 USD. If you only want 300