I think my Mimi is very rumbly and strong. They must be made differently or something because some people say theirs is weak and buzzy. I think the G-Ki is about the same amount of rumbly as Mimi, but it feels a little more rumbly sometimes because it doesn't get to as high of a speed. Sometimes when you get to higher speeds things start to feel buzzier just because of the power, I think. The G-Ki is nowhere near the power of Mimi, sadly. I'd rank Mimi at a five, where the G-Ki at the base is about a four and the head is a three. I'd kill for a G-Ki with the strength of Mimi. Even with the weaker power, the rumbly vibrations were satisfying enough to make up for it.
The G-Ki is AWESOME. I love mine. If you have to have super strong vibrations at the insertable part, it might not be enough. You could look into the Jopen's. They cost more, but they are both strong AND rumbly. However, I can't get a G spot orgasm from any of them. They just give me regular orgasms. I have a particular G spot, so I don't know if I'd go off of me. I don't have the Vr9 yet and I have high hopes for that one maybe giving me a G spot orgasm. We shall see when I get one.