I haven’t heard anything about them being OP. They look pretty fun and adaptable. https://www.goonhammer.com/necromunday-houses-er-cults-of-the-underhive-genestealer-cults/
i think they also have access to the new wyrd powers in the Book of Outcasts, which could be a game changer.
you can really mod any models you want as long as the weapons are representative, which is part of the fun. You’re limited to two aberrants