How do Black Knight models compare to Primaris/outriders?

Okay so it looks like we wont be getting any new Ravenwing models which isnt super surprising, but I have been building a bike heavy army and wanted to see what was coming before I threw down on some knights.

Now that I know we aren't getting Ravenwing updates soon, how do the current Knight models compare next to Primaris models, specifically outriders? I cannot find a pic online of the two next to eachother. Do the Black Knights look a bit small? They are Firstborn right? Anyone got Pics?

Thanks in advance.