I don't know about the original, but I actually own the Model D Sport STP from number one factory.
I also own the Gen 2S Peecock from Peecock products.
Like I said I'm not sure about the original number one, but the Model D is hard as a rock. Very easy to pee with because it is inflexible and has a deep catcher. Doesn't look like I'm sporting a boner or anything. It's just right when it comes to sitting down and looking like I have a "natural bulge" or standing to pee.... but it's not very flexible which makes it uncomfortable for me after a few hours of wearing it. It's literally a penis shaped funnel and it looks good and all, they had the right idea, but I'm scared that if I were to ever try moving the shaft up or down like you had mentioned, I might break it. That's just how stiff it is. It stays in one spot and doesn't move.
It was the affordable option, but I ended up going with the Peecock. Before they made the Gen 3, I bought the 2s. This one is A LOT more realistic. Harder to pee in than the Model D, but I think the Gen 3 has a deeper catcher for guys like me who wait too long to go to the bathroom.
If you'd like, I could show you the harnesses for both, and the actual STPs themselves and give you the true pros and cons list of what I like and dislike about each. I'll take pictures of them on my desk. Kinda hard to show the inflexibility without video though.