Keith, I've listened to your singing many times now, and you're a great all-round singer! Must be very fun to have you in a band when you're that versatile.
If I'm going to give you some critique, it's this: it sounds to me like you're playing it safe all the time. If I'm wrong, disregard this paragraph, and I apologise for my misinterpretation!
Anyway, being sturdy and reliable is of course great (especially in a band environment), but sometimes metal urges... no, commands you to release the inner beast and manifest itself within your voice!
It might be hard to let go of one's inhibitions and hit the correct notes at first, but once you're past the threshold you're home.
I might be biased, seeing as I'm nothing but power... but I hope you understand what I'm getting at!