I've been diving a SP Classic Plus with an AIR2 for the past three years. I've never been happier with a BC setup. When I'm instructing, I also have a traditional octopus. I also have seen a lot of postings that bash the AIR2, but I am a fan of the product. I think that an inexperienced panicked diver is more apt to retrieve a second stage from your mouth than from an octo holder and you will have an easier time finding an AIR2 than your octo in the chaos. I am very aware that this isn't the way that it is suppose to be, but out-of-air emergencies don't always follow the rules.
If you are relatively new to diving, you've got to ask yourself how much time you plan to spend at the surface conversing with your buddies. The back-inflation of the Knighthawk will tend to put your face in the water, while the Glide is more apt to surround you with buoyancy and keep you in an upright position. I think that the Glide is marginally safer if you surface unconcious since you are more likely to be upright.
I'm glad to hear that you are diving ScubaPro . . . VERY well constructed BCs. diver-doc