Here in the British GT we have (later this summer) M Sport (the Ford WRC team) running the Bentley.
And also in its own series
The Ginetta (Zytek) G40, G50 & G55 (one of those is the base for a GT4 spec car).
http://ginetta.co.uk/
So there are other front engined cars raced.
(Ginetta is available for the smaller GT12 class)