I've never ridden the Circuit, but I've been riding a NS Legacy for about 5 years now. They make invincible snowboards. Can't say enough good things about them and I think if you ask around on this forum, you'll find a lot of the same opinions. Plus they have the longest warranty in the business - 3 years!
The circuit should be a pretty forgiving board, and it's reverse camber which is all the rage these days I guess. Might take a day to get used to if you've been riding regular camber. It's not real damp so high speeds might be a little sketchy, but for a beginner it should be alright.