No, assuming that Ryuki and Gaim is going to be similar due to the fact that they simply both "has a lot of Riders" is a pretty superficial thing.
Similarity doesn't mean you can expect everything to go exactly alike. Like Gen Urobuchi said, he simply took a few key inspirations from previous series, and made it his own.
Experienced Toku Viewers have to stop viewing the new shows from the perception of a fan who's seen and loved previous shows, because that creates a bias that most people would probably end up saying "nah, this isn't for me, it just copied Ryuki/Kabuto's Rider Fights and Faiz's misunderstandings".
Take it for what it is, instead of constantly trying to compare every series with one another, it's getting really ridiculous the amount of threads where people go "no, this is awesome, no that's awesome, no this ripped it off, but this is new!". Then finally, we can move on to discussions about the shows that's actually enjoyable instead of nitpicking things all the time. I grew up with Kamen Rider, pretty much saw Kuuga when it first aired, I'm 19 now, and Gaim does do the references to each Riders in the part pretty well, all the while managing to be it's own thing, unlike that godawful Wizard and Fourze that I had to skip.