Have you tried searching this forum? There’s quite alot of posts about the G9. Other stuff you might want to look up is the performance of the TTL system that is possible with the Ike housing and strobe combination. There’s also more on wetpixel (http://www.wetpixel.com). There are threads there with example pictures… Again, I’d suggest searching the forum.
I don’t have a G9, but from what I’ve seen, its a very capable camera. Its close focus ability is good for macro, however the lens is a very long zoom, so it is physically long (at maximum zoom). This causes the housings to have a long port body, which blocks the camera’s flash when you are close up. For best results, you will need the strobe you are talking about.
regards