Actually Most pro gamers these days tend to use whatever a sponsor tells them, I only know of about 5 players who attended the Code A Qualifiers used Leopolds.
Actually, Maru is using a leopold, Innovation too. I know marineking is also using one. They're all on diffrents team who don't have a particular sponsor for their keyboards. They are using leopold because they like it, that's definitely what i think. It doesn't look like if they were under contract or something like this.
Both maru and Innovation use filco keyboards, A couple of years back a lot of the pros used leopolds but they are horribly expensive by comparison.
http://imgur.com/a/ixDhRThis is a good reference but they are mostly out of date.
Last time I saw Innovation play live was at DH:O and he had a White and blue Filco with an Axiom escape key.
The keyboard Maru was using last week is 750R, Having spoken to him though his normal use board is an LZ.
Marine King has multiple keyboards his favourite according to him is a Qsenn Dt-35with Black and white caps.
He owns 2 Leopolds from memory one of which is white with red switches and the other is a ninja white with Browns. He also has a Filco and a ducky but we rarely see them.