I’ve just written a blog post on this topic after reading a very interesting article by casting director Mark Estdale.  He answers the question of whether to include music and FX on the showreel  Also how long should they be? What voices should they include?
You can read my post on gaming voice reels on the chrisradley.co.uk website and you can read Mark’s article on the Linked In website

Chris Radley
dVoiceBox