Can I just say how much I love the designs in this manga? Rapid Rabbit, the Kaijin themselves, Honey Trap, they're all so good! And X's design is basically perfect. It's got that menacing vibe the main villain needs while at the same time bearing a resemblance to Rapid Rabbit, which is probably completely intended since Hayate's dimension tool was made from X herself. Having X's kaijin form be like a dark, evil mirror to Rapid Rabbit actually reminds me a lot of Kuuga and Daguva.
Though I will say I expect some sort of upgraded form or SOMETHING for the very soon approaching battle with X, since they I doubt we'd get to see her without the cloak if it wasn't. Maybe some sort of fusion or combination attack with Honey? Regardless, given this is very much a toku manga I will be incredibly surprised if neither Hayate or Honey get some sort of upgraded from by the end of it.
Tl;DR I love this manga to death
As a fan of Kamen rider, it really does reminds me of the similarity between Kuuga and Daguva (similar but different, especially with the colours being inverted to one another). And I also wholeheartedly agree with what you said. Given the fact that the author actually likes rider shows, I really do believe we will get some sort of upgrade form or some sort, it would be unfortunate if we didn't get anything tho.