Steve, the open comb does allow a lot more exposure to the blade, obviously. You may want to start with the guard bar, but once you have the hang of it, open combs and "slants" that allow more blade exposure can be great for heavy beards or a really close shave.
The standard bar is probably the best to begin with. But once your technique is good and you have the prep down pat, the world is your oyster. You can try any razor. I have several open comb razors that do quite well. But I would learn on (e.g.) the regular HD, not the open-comb.