I see they have some new models on the .CN site. The 520 looks sweet

Outside of the US the 500 HO is called a 520--we don't call it that in the US for branding purposes.  You may have noticed the 520S, though.  That'll be a new model in the US for 2017 we'll be calling the 500S.  It's a 500 engine on a 400-style 1-up chassis, which should rip pretty hard.

I thought the 500ho is the 550?

Yes, cos. The 500ho is called 550 in other markets.
The 400 or 425 or 450 are all the same also. Next up is the 520, it shares the same chassis as the 400........ But a 500 engine.
For some strange reason cfmoto is all over the place on stickers.
And adding cc where there aren't 

By calling the same model many different things, they add confusion. I don't understand it. Reminds me of cheap products that get a different sticker slapped on them depending on who ordered them. I know this is not the case, but it doesn't help. We already have reviews being left for the 500ho when what they really had was a cf500. Not the same machine, but people will read all the complaints and assume they are.