Brian's Unique Oblique, I finally was able to get my hands on, had a Nikko G with it when I purchased it.
You are most fortunate! I had the Devil's own time trying to legitimately acquire a UniqueOblique. In the end I had to stop as it was simply wasting too much of my time trying to watch for them to magically appear like mushrooms after the rains. That was when a kindly FPN member stepped in and offered to make a holder for me (pictures elsewhere on this forum).
As for the G nibs, I started with a Zebra G and really like it. As others note it takes abuse in its stride and lasts a good long time. In fact, I am still on my first one, and this is several months after taking up this hobby! Admittedly i do not do as much writing as others, but even so...
I also have a Nikko G (just the one) and although the shape is subtly different I don't notice that much difference in writing character. However, I am still a beginner so it is quite possible - highly likely in fact - that I am not sensitive enough to feel the difference yet.
Overall I would like to say that there is nothing scary about using any nib. I have used Gillott 303s and Leonardt Principals and so on. None are beyond use by a beginner in my opinion, as long as a modicum of care and patience is applied. If someone takes a Principal and mashes it into the page like a ballpoint (sorry for the bad language!) then all bets are off.