I would trust anything HOG makes to work well and be an excellent value. I own 4 D1 first stages and 6 Classic second stages. As I see it, the main advantage of the Zenith is less likelihood of the purge getting fouled by sediment. So if that's a risk of this with your diving configuration and the locations you like to dive, it would be worth the extra few bucks. Or if you just think the Zenith just looks cool, well that's fine too. I can't imagine the Zenith has any DISadvantages compared to the Classic 2nd, and the internal parts are all identical.