Chunking is a good idea, but you'll have to do it yourself. A few of the columns in our application got quite large (maybe ~150MB) and the failure mode was RPC timeout exceptions. Nodes couldn't always move that much data across our data center interconnect in the default 10 seconds. With enough heap and a faster network you could probably get by without chunking, but it's not ideal.
I'm being asked whether we can serve an "object", which I assume is a blob, of 750MB size?
I guess the real question is of how to chunk it and/or even it's possible to chunk it.