Interesting lighting rig… I think you could simplify it a bit, and use AO or AAO to lighten up the really dark parts. A few spots around the outside would give you a nice will lit render IMO.
http://wiki.blender.org/index.php/Manual/Ambient_Occlusion (slightly out of date but im sure you can figure it out).
I also suggest you explore the edgesplit modifier, it will make your rendered mesh look a lot cleaner.
Otherwise, it’s a good start… just makes sure all the normals are facing the right way. And I’m a fan of doing clay renders until the modelling is finished, but for projects like this it probably wont make a difference. Up to you.