I don't have, nor do I intend to get, Combiner Wars Motormaster, so I cannot speak to the horns at all. But I just got in my hips for Optimus today. (Well, they probably came yesterday, what with today being Sunday and all. But I only checked the mail today.) Anyway, I rather like them!
Prime himself is able to stand with his legs spread at a proper angle so that his feet (which are molded at an angle) are actually able to be flat to the ground.
And, while I don't have any limbs for it yet, the combined mode is also able to have his legs straight. Quite an improvement!
I also received the antenna for Superion, but since I am waiting on Takara's Superion, I don't have Silverbolt in hand yet. So I'll have to wait before I can install those and see how well they fit.
But so far, this having been the first things I've ordered from Nonnef, I am happy with my experience.