Geode is write-intensive, and generally optimizes for consistency over availability. That being said - there's a lot built into Geode to ensure availability as well.
Redis and in-memory data grids are pretty different animals. I would characterize IMDG's like Geode to be concurrent write intensive, and have flexible data models. It also scales out better than Redis in a more automated fashion.
Redis is a great read-intensive cache. It also has a powerful data model, but you have to use their data models. Example: If you want to run calculations on lists or sets, they have powerful operations you can call.
IMDG's such as Geode were built with the rise of automated trading in the finance industry.