I’m thinking of signing up here, but are the perks really that different between the various membership levels?

Each class has its own characteristics. After that, meet with them, hear what they have to say, and decide for yourself.

I don’t think there’s a major difference in the benefits themselves. The differences in what you can do with each class are listed under “Detailed Services Available” on the page below: https://universe-club.jp/men/price/ However, you can only make offers to women in the same class as yours or a lower class. So it seems most efficient to join as Platinum, then upgrade if there’s someone you want to make an offer to who’s in the Black class. That said, if you don’t want to go through that hassle and you always prefer being in the highest class, then it may be better to join as Black and decide for yourself after a year, once you’ve gotten a feel for how things work. When you think about it, making the decision yourself is probably the most rational approach.