I like H shaped yoyos a lot, so I think the shape of the iCEBERG is great. However, my favorite hybrid is probably the POM Draupnir. It is light and stable and nimble and you can really get it moving with ease.
The iceberg is great. One of my favorites for sure. If you like fingerspins you will not be disapointed. However, i have not played the Refraction so i cannot give you a comparison.
from left to right: iceberg (H), refraction (O-ish), ippon (V), gamma crash (W)
This should also be relevant to @zslane’s interests as these are true hybrids by most definitions … and it turns out they all have fairly unique shapes!